linux/lib/kobject.c

1131 lines
28 KiB

2013-09-11 22:29:05 -04:00
2013-09-11 22:29:05 -04:00
2013-09-11 22:29:05 -04:00
2013-09-11 22:29:05 -04:00
sysfs: drop kobj_ns_type handling, take #2 The way namespace tags are implemented in sysfs is more complicated than necessary. As each tag is a pointer value and required to be non-NULL under a namespace enabled parent, there's no need to record separately what type each tag is. If multiple namespace types are needed, which currently aren't, we can simply compare the tag to a set of allowed tags in the superblock assuming that the tags, being pointers, won't have the same value across multiple types. This patch rips out kobj_ns_type handling from sysfs. sysfs now has an enable switch to turn on namespace under a node. If enabled, all children are required to have non-NULL namespace tags and filtered against the super_block's tag. kobject namespace determination is now performed in lib/kobject.c::create_dir() making sysfs_read_ns_type() unnecessary. The sanity checks are also moved. create_dir() is restructured to ease such addition. This removes most kobject namespace knowledge from sysfs proper which will enable proper separation and layering of sysfs. This is the second try. The first one was cb26a311578e ("sysfs: drop kobj_ns_type handling") which tried to automatically enable namespace if there are children with non-NULL namespace tags; however, it was broken for symlinks as they should inherit the target's tag iff namespace is enabled in the parent. This led to namespace filtering enabled incorrectly for wireless net class devices through phy80211 symlinks and thus network configuration failure. a1212d278c05 ("Revert "sysfs: drop kobj_ns_type handling"") reverted the commit. This shouldn't introduce any behavior changes, for real. v2: Dummy implementation of sysfs_enable_ns() for !CONFIG_SYSFS was missing and caused build failure. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-23 18:01:46 -05:00
2013-09-11 22:29:05 -04:00
sysfs: drop kobj_ns_type handling, take #2 The way namespace tags are implemented in sysfs is more complicated than necessary. As each tag is a pointer value and required to be non-NULL under a namespace enabled parent, there's no need to record separately what type each tag is. If multiple namespace types are needed, which currently aren't, we can simply compare the tag to a set of allowed tags in the superblock assuming that the tags, being pointers, won't have the same value across multiple types. This patch rips out kobj_ns_type handling from sysfs. sysfs now has an enable switch to turn on namespace under a node. If enabled, all children are required to have non-NULL namespace tags and filtered against the super_block's tag. kobject namespace determination is now performed in lib/kobject.c::create_dir() making sysfs_read_ns_type() unnecessary. The sanity checks are also moved. create_dir() is restructured to ease such addition. This removes most kobject namespace knowledge from sysfs proper which will enable proper separation and layering of sysfs. This is the second try. The first one was cb26a311578e ("sysfs: drop kobj_ns_type handling") which tried to automatically enable namespace if there are children with non-NULL namespace tags; however, it was broken for symlinks as they should inherit the target's tag iff namespace is enabled in the parent. This led to namespace filtering enabled incorrectly for wireless net class devices through phy80211 symlinks and thus network configuration failure. a1212d278c05 ("Revert "sysfs: drop kobj_ns_type handling"") reverted the commit. This shouldn't introduce any behavior changes, for real. v2: Dummy implementation of sysfs_enable_ns() for !CONFIG_SYSFS was missing and caused build failure. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-23 18:01:46 -05:00
sysfs: drop kobj_ns_type handling, take #2 The way namespace tags are implemented in sysfs is more complicated than necessary. As each tag is a pointer value and required to be non-NULL under a namespace enabled parent, there's no need to record separately what type each tag is. If multiple namespace types are needed, which currently aren't, we can simply compare the tag to a set of allowed tags in the superblock assuming that the tags, being pointers, won't have the same value across multiple types. This patch rips out kobj_ns_type handling from sysfs. sysfs now has an enable switch to turn on namespace under a node. If enabled, all children are required to have non-NULL namespace tags and filtered against the super_block's tag. kobject namespace determination is now performed in lib/kobject.c::create_dir() making sysfs_read_ns_type() unnecessary. The sanity checks are also moved. create_dir() is restructured to ease such addition. This removes most kobject namespace knowledge from sysfs proper which will enable proper separation and layering of sysfs. This is the second try. The first one was cb26a311578e ("sysfs: drop kobj_ns_type handling") which tried to automatically enable namespace if there are children with non-NULL namespace tags; however, it was broken for symlinks as they should inherit the target's tag iff namespace is enabled in the parent. This led to namespace filtering enabled incorrectly for wireless net class devices through phy80211 symlinks and thus network configuration failure. a1212d278c05 ("Revert "sysfs: drop kobj_ns_type handling"") reverted the commit. This shouldn't introduce any behavior changes, for real. v2: Dummy implementation of sysfs_enable_ns() for !CONFIG_SYSFS was missing and caused build failure. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-23 18:01:46 -05:00
sysfs: drop kobj_ns_type handling, take #2 The way namespace tags are implemented in sysfs is more complicated than necessary. As each tag is a pointer value and required to be non-NULL under a namespace enabled parent, there's no need to record separately what type each tag is. If multiple namespace types are needed, which currently aren't, we can simply compare the tag to a set of allowed tags in the superblock assuming that the tags, being pointers, won't have the same value across multiple types. This patch rips out kobj_ns_type handling from sysfs. sysfs now has an enable switch to turn on namespace under a node. If enabled, all children are required to have non-NULL namespace tags and filtered against the super_block's tag. kobject namespace determination is now performed in lib/kobject.c::create_dir() making sysfs_read_ns_type() unnecessary. The sanity checks are also moved. create_dir() is restructured to ease such addition. This removes most kobject namespace knowledge from sysfs proper which will enable proper separation and layering of sysfs. This is the second try. The first one was cb26a311578e ("sysfs: drop kobj_ns_type handling") which tried to automatically enable namespace if there are children with non-NULL namespace tags; however, it was broken for symlinks as they should inherit the target's tag iff namespace is enabled in the parent. This led to namespace filtering enabled incorrectly for wireless net class devices through phy80211 symlinks and thus network configuration failure. a1212d278c05 ("Revert "sysfs: drop kobj_ns_type handling"") reverted the commit. This shouldn't introduce any behavior changes, for real. v2: Dummy implementation of sysfs_enable_ns() for !CONFIG_SYSFS was missing and caused build failure. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-23 18:01:46 -05:00
sysfs: drop kobj_ns_type handling, take #2 The way namespace tags are implemented in sysfs is more complicated than necessary. As each tag is a pointer value and required to be non-NULL under a namespace enabled parent, there's no need to record separately what type each tag is. If multiple namespace types are needed, which currently aren't, we can simply compare the tag to a set of allowed tags in the superblock assuming that the tags, being pointers, won't have the same value across multiple types. This patch rips out kobj_ns_type handling from sysfs. sysfs now has an enable switch to turn on namespace under a node. If enabled, all children are required to have non-NULL namespace tags and filtered against the super_block's tag. kobject namespace determination is now performed in lib/kobject.c::create_dir() making sysfs_read_ns_type() unnecessary. The sanity checks are also moved. create_dir() is restructured to ease such addition. This removes most kobject namespace knowledge from sysfs proper which will enable proper separation and layering of sysfs. This is the second try. The first one was cb26a311578e ("sysfs: drop kobj_ns_type handling") which tried to automatically enable namespace if there are children with non-NULL namespace tags; however, it was broken for symlinks as they should inherit the target's tag iff namespace is enabled in the parent. This led to namespace filtering enabled incorrectly for wireless net class devices through phy80211 symlinks and thus network configuration failure. a1212d278c05 ("Revert "sysfs: drop kobj_ns_type handling"") reverted the commit. This shouldn't introduce any behavior changes, for real. v2: Dummy implementation of sysfs_enable_ns() for !CONFIG_SYSFS was missing and caused build failure. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-23 18:01:46 -05:00
kobject: Fix slab-out-of-bounds in fill_kobj_path() In kobject_get_path(), if kobj->name is changed between calls get_kobj_path_length() and fill_kobj_path() and the length becomes longer, then fill_kobj_path() will have an out-of-bounds bug. The actual current problem occurs when the ixgbe probe. In ixgbe_mii_bus_init(), if the length of netdev->dev.kobj.name length becomes longer, out-of-bounds will occur. cpu0 cpu1 ixgbe_probe register_netdev(netdev) netdev_register_kobject device_add kobject_uevent // Sending ADD events systemd-udevd // rename netdev dev_change_name device_rename kobject_rename ixgbe_mii_bus_init | mdiobus_register | __mdiobus_register | device_register | device_add | kobject_uevent | kobject_get_path | len = get_kobj_path_length // old name | path = kzalloc(len, gfp_mask); | kobj->name = name; /* name length becomes * longer */ fill_kobj_path /* kobj path length is * longer than path, * resulting in out of * bounds when filling path */ This is the kasan report: ================================================================== BUG: KASAN: slab-out-of-bounds in fill_kobj_path+0x50/0xc0 Write of size 7 at addr ff1100090573d1fd by task kworker/28:1/673 Workqueue: events work_for_cpu_fn Call Trace: <TASK> dump_stack_lvl+0x34/0x48 print_address_description.constprop.0+0x86/0x1e7 print_report+0x36/0x4f kasan_report+0xad/0x130 kasan_check_range+0x35/0x1c0 memcpy+0x39/0x60 fill_kobj_path+0x50/0xc0 kobject_get_path+0x5a/0xc0 kobject_uevent_env+0x140/0x460 device_add+0x5c7/0x910 __mdiobus_register+0x14e/0x490 ixgbe_probe.cold+0x441/0x574 [ixgbe] local_pci_probe+0x78/0xc0 work_for_cpu_fn+0x26/0x40 process_one_work+0x3b6/0x6a0 worker_thread+0x368/0x520 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30 This reproducer triggers that bug: while: do rmmod ixgbe sleep 0.5 modprobe ixgbe sleep 0.5 When calling fill_kobj_path() to fill path, if the name length of kobj becomes longer, return failure and retry. This fixes the problem. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Wang Hai <wanghai38@huawei.com> Link: https://lore.kernel.org/r/20221220012143.52141-1-wanghai38@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-12-20 09:21:43 +08:00
kobject: Fix slab-out-of-bounds in fill_kobj_path() In kobject_get_path(), if kobj->name is changed between calls get_kobj_path_length() and fill_kobj_path() and the length becomes longer, then fill_kobj_path() will have an out-of-bounds bug. The actual current problem occurs when the ixgbe probe. In ixgbe_mii_bus_init(), if the length of netdev->dev.kobj.name length becomes longer, out-of-bounds will occur. cpu0 cpu1 ixgbe_probe register_netdev(netdev) netdev_register_kobject device_add kobject_uevent // Sending ADD events systemd-udevd // rename netdev dev_change_name device_rename kobject_rename ixgbe_mii_bus_init | mdiobus_register | __mdiobus_register | device_register | device_add | kobject_uevent | kobject_get_path | len = get_kobj_path_length // old name | path = kzalloc(len, gfp_mask); | kobj->name = name; /* name length becomes * longer */ fill_kobj_path /* kobj path length is * longer than path, * resulting in out of * bounds when filling path */ This is the kasan report: ================================================================== BUG: KASAN: slab-out-of-bounds in fill_kobj_path+0x50/0xc0 Write of size 7 at addr ff1100090573d1fd by task kworker/28:1/673 Workqueue: events work_for_cpu_fn Call Trace: <TASK> dump_stack_lvl+0x34/0x48 print_address_description.constprop.0+0x86/0x1e7 print_report+0x36/0x4f kasan_report+0xad/0x130 kasan_check_range+0x35/0x1c0 memcpy+0x39/0x60 fill_kobj_path+0x50/0xc0 kobject_get_path+0x5a/0xc0 kobject_uevent_env+0x140/0x460 device_add+0x5c7/0x910 __mdiobus_register+0x14e/0x490 ixgbe_probe.cold+0x441/0x574 [ixgbe] local_pci_probe+0x78/0xc0 work_for_cpu_fn+0x26/0x40 process_one_work+0x3b6/0x6a0 worker_thread+0x368/0x520 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30 This reproducer triggers that bug: while: do rmmod ixgbe sleep 0.5 modprobe ixgbe sleep 0.5 When calling fill_kobj_path() to fill path, if the name length of kobj becomes longer, return failure and retry. This fixes the problem. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Wang Hai <wanghai38@huawei.com> Link: https://lore.kernel.org/r/20221220012143.52141-1-wanghai38@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-12-20 09:21:43 +08:00
kobject: Fix slab-out-of-bounds in fill_kobj_path() In kobject_get_path(), if kobj->name is changed between calls get_kobj_path_length() and fill_kobj_path() and the length becomes longer, then fill_kobj_path() will have an out-of-bounds bug. The actual current problem occurs when the ixgbe probe. In ixgbe_mii_bus_init(), if the length of netdev->dev.kobj.name length becomes longer, out-of-bounds will occur. cpu0 cpu1 ixgbe_probe register_netdev(netdev) netdev_register_kobject device_add kobject_uevent // Sending ADD events systemd-udevd // rename netdev dev_change_name device_rename kobject_rename ixgbe_mii_bus_init | mdiobus_register | __mdiobus_register | device_register | device_add | kobject_uevent | kobject_get_path | len = get_kobj_path_length // old name | path = kzalloc(len, gfp_mask); | kobj->name = name; /* name length becomes * longer */ fill_kobj_path /* kobj path length is * longer than path, * resulting in out of * bounds when filling path */ This is the kasan report: ================================================================== BUG: KASAN: slab-out-of-bounds in fill_kobj_path+0x50/0xc0 Write of size 7 at addr ff1100090573d1fd by task kworker/28:1/673 Workqueue: events work_for_cpu_fn Call Trace: <TASK> dump_stack_lvl+0x34/0x48 print_address_description.constprop.0+0x86/0x1e7 print_report+0x36/0x4f kasan_report+0xad/0x130 kasan_check_range+0x35/0x1c0 memcpy+0x39/0x60 fill_kobj_path+0x50/0xc0 kobject_get_path+0x5a/0xc0 kobject_uevent_env+0x140/0x460 device_add+0x5c7/0x910 __mdiobus_register+0x14e/0x490 ixgbe_probe.cold+0x441/0x574 [ixgbe] local_pci_probe+0x78/0xc0 work_for_cpu_fn+0x26/0x40 process_one_work+0x3b6/0x6a0 worker_thread+0x368/0x520 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30 This reproducer triggers that bug: while: do rmmod ixgbe sleep 0.5 modprobe ixgbe sleep 0.5 When calling fill_kobj_path() to fill path, if the name length of kobj becomes longer, return failure and retry. This fixes the problem. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Wang Hai <wanghai38@huawei.com> Link: https://lore.kernel.org/r/20221220012143.52141-1-wanghai38@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-12-20 09:21:43 +08:00
kobject: Fix slab-out-of-bounds in fill_kobj_path() In kobject_get_path(), if kobj->name is changed between calls get_kobj_path_length() and fill_kobj_path() and the length becomes longer, then fill_kobj_path() will have an out-of-bounds bug. The actual current problem occurs when the ixgbe probe. In ixgbe_mii_bus_init(), if the length of netdev->dev.kobj.name length becomes longer, out-of-bounds will occur. cpu0 cpu1 ixgbe_probe register_netdev(netdev) netdev_register_kobject device_add kobject_uevent // Sending ADD events systemd-udevd // rename netdev dev_change_name device_rename kobject_rename ixgbe_mii_bus_init | mdiobus_register | __mdiobus_register | device_register | device_add | kobject_uevent | kobject_get_path | len = get_kobj_path_length // old name | path = kzalloc(len, gfp_mask); | kobj->name = name; /* name length becomes * longer */ fill_kobj_path /* kobj path length is * longer than path, * resulting in out of * bounds when filling path */ This is the kasan report: ================================================================== BUG: KASAN: slab-out-of-bounds in fill_kobj_path+0x50/0xc0 Write of size 7 at addr ff1100090573d1fd by task kworker/28:1/673 Workqueue: events work_for_cpu_fn Call Trace: <TASK> dump_stack_lvl+0x34/0x48 print_address_description.constprop.0+0x86/0x1e7 print_report+0x36/0x4f kasan_report+0xad/0x130 kasan_check_range+0x35/0x1c0 memcpy+0x39/0x60 fill_kobj_path+0x50/0xc0 kobject_get_path+0x5a/0xc0 kobject_uevent_env+0x140/0x460 device_add+0x5c7/0x910 __mdiobus_register+0x14e/0x490 ixgbe_probe.cold+0x441/0x574 [ixgbe] local_pci_probe+0x78/0xc0 work_for_cpu_fn+0x26/0x40 process_one_work+0x3b6/0x6a0 worker_thread+0x368/0x520 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30 This reproducer triggers that bug: while: do rmmod ixgbe sleep 0.5 modprobe ixgbe sleep 0.5 When calling fill_kobj_path() to fill path, if the name length of kobj becomes longer, return failure and retry. This fixes the problem. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Wang Hai <wanghai38@huawei.com> Link: https://lore.kernel.org/r/20221220012143.52141-1-wanghai38@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-12-20 09:21:43 +08:00
kobject: Fix slab-out-of-bounds in fill_kobj_path() In kobject_get_path(), if kobj->name is changed between calls get_kobj_path_length() and fill_kobj_path() and the length becomes longer, then fill_kobj_path() will have an out-of-bounds bug. The actual current problem occurs when the ixgbe probe. In ixgbe_mii_bus_init(), if the length of netdev->dev.kobj.name length becomes longer, out-of-bounds will occur. cpu0 cpu1 ixgbe_probe register_netdev(netdev) netdev_register_kobject device_add kobject_uevent // Sending ADD events systemd-udevd // rename netdev dev_change_name device_rename kobject_rename ixgbe_mii_bus_init | mdiobus_register | __mdiobus_register | device_register | device_add | kobject_uevent | kobject_get_path | len = get_kobj_path_length // old name | path = kzalloc(len, gfp_mask); | kobj->name = name; /* name length becomes * longer */ fill_kobj_path /* kobj path length is * longer than path, * resulting in out of * bounds when filling path */ This is the kasan report: ================================================================== BUG: KASAN: slab-out-of-bounds in fill_kobj_path+0x50/0xc0 Write of size 7 at addr ff1100090573d1fd by task kworker/28:1/673 Workqueue: events work_for_cpu_fn Call Trace: <TASK> dump_stack_lvl+0x34/0x48 print_address_description.constprop.0+0x86/0x1e7 print_report+0x36/0x4f kasan_report+0xad/0x130 kasan_check_range+0x35/0x1c0 memcpy+0x39/0x60 fill_kobj_path+0x50/0xc0 kobject_get_path+0x5a/0xc0 kobject_uevent_env+0x140/0x460 device_add+0x5c7/0x910 __mdiobus_register+0x14e/0x490 ixgbe_probe.cold+0x441/0x574 [ixgbe] local_pci_probe+0x78/0xc0 work_for_cpu_fn+0x26/0x40 process_one_work+0x3b6/0x6a0 worker_thread+0x368/0x520 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30 This reproducer triggers that bug: while: do rmmod ixgbe sleep 0.5 modprobe ixgbe sleep 0.5 When calling fill_kobj_path() to fill path, if the name length of kobj becomes longer, return failure and retry. This fixes the problem. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Wang Hai <wanghai38@huawei.com> Link: https://lore.kernel.org/r/20221220012143.52141-1-wanghai38@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-12-20 09:21:43 +08:00
2013-09-11 22:29:05 -04:00
2013-09-11 22:29:05 -04:00
2013-09-11 22:29:05 -04:00
kobject: WARN as tip when call kobject_get() to a kobject not initialized call kobject_get() to kojbect that is not initalized or released will only leave following like call trace to us: -----------[ cut here ]------------ [ 54.545816] WARNING: CPU: 0 PID: 213 at include/linux/kref.h:47 kobject_get+0x41/0x50() [ 54.642595] Modules linked in: i2c_i801(+) mfd_core shpchp(+) acpi_cpufreq(+) edac_core ioatdma(+) xfs libcrc32c ast syscopyarea ixgbe sysfillrect sysimgblt sr_mod sd_mod drm_kms_helper igb mdio cdrom e1000e ahci dca ttm libahci uas drm i2c_algo_bit ptp megaraid_sas libata usb_storage i2c_core pps_core dm_mirror dm_region_hash dm_log dm_mod [ 55.007264] CPU: 0 PID: 213 Comm: kworker/0:2 Not tainted 3.18.5 [ 55.099970] Hardware name: Oracle Corporation SUN FIRE X4170 M2 SERVER /ASSY,MOTHERBOARD,X4170, BIOS 08120104 05/08/2012 [ 55.239736] Workqueue: kacpi_notify acpi_os_execute_deferred [ 55.308598] 0000000000000000 00000000bd730b61 ffff88046742baf8 ffffffff816b7edb [ 55.398305] 0000000000000000 0000000000000000 ffff88046742bb38 ffffffff81078ae1 [ 55.488040] ffff88046742bbd8 ffff8806706b3000 0000000000000292 0000000000000000 [ 55.577776] Call Trace: [ 55.608228] [<ffffffff816b7edb>] dump_stack+0x46/0x58 [ 55.670895] [<ffffffff81078ae1>] warn_slowpath_common+0x81/0xa0 [ 55.743952] [<ffffffff81078bfa>] warn_slowpath_null+0x1a/0x20 [ 55.814929] [<ffffffff8130d0d1>] kobject_get+0x41/0x50 [ 55.878654] [<ffffffff8153e955>] cpufreq_cpu_get+0x75/0xc0 [ 55.946528] [<ffffffff8153f37e>] cpufreq_update_policy+0x2e/0x1f0 The above issue was casued by a race condition, if there is a WARN in kobject_get() of the kobject is not initialized, that would save us much time to debug it. Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-03-12 13:04:16 +09:00
kobject: WARN as tip when call kobject_get() to a kobject not initialized call kobject_get() to kojbect that is not initalized or released will only leave following like call trace to us: -----------[ cut here ]------------ [ 54.545816] WARNING: CPU: 0 PID: 213 at include/linux/kref.h:47 kobject_get+0x41/0x50() [ 54.642595] Modules linked in: i2c_i801(+) mfd_core shpchp(+) acpi_cpufreq(+) edac_core ioatdma(+) xfs libcrc32c ast syscopyarea ixgbe sysfillrect sysimgblt sr_mod sd_mod drm_kms_helper igb mdio cdrom e1000e ahci dca ttm libahci uas drm i2c_algo_bit ptp megaraid_sas libata usb_storage i2c_core pps_core dm_mirror dm_region_hash dm_log dm_mod [ 55.007264] CPU: 0 PID: 213 Comm: kworker/0:2 Not tainted 3.18.5 [ 55.099970] Hardware name: Oracle Corporation SUN FIRE X4170 M2 SERVER /ASSY,MOTHERBOARD,X4170, BIOS 08120104 05/08/2012 [ 55.239736] Workqueue: kacpi_notify acpi_os_execute_deferred [ 55.308598] 0000000000000000 00000000bd730b61 ffff88046742baf8 ffffffff816b7edb [ 55.398305] 0000000000000000 0000000000000000 ffff88046742bb38 ffffffff81078ae1 [ 55.488040] ffff88046742bbd8 ffff8806706b3000 0000000000000292 0000000000000000 [ 55.577776] Call Trace: [ 55.608228] [<ffffffff816b7edb>] dump_stack+0x46/0x58 [ 55.670895] [<ffffffff81078ae1>] warn_slowpath_common+0x81/0xa0 [ 55.743952] [<ffffffff81078bfa>] warn_slowpath_null+0x1a/0x20 [ 55.814929] [<ffffffff8130d0d1>] kobject_get+0x41/0x50 [ 55.878654] [<ffffffff8153e955>] cpufreq_cpu_get+0x75/0xc0 [ 55.946528] [<ffffffff8153f37e>] cpufreq_update_policy+0x2e/0x1f0 The above issue was casued by a race condition, if there is a WARN in kobject_get() of the kobject is not initialized, that would save us much time to debug it. Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-03-12 13:04:16 +09:00
kobject: fix kset_find_obj() race with concurrent last kobject_put() Anatol Pomozov identified a race condition that hits module unloading and re-loading. To quote Anatol: "This is a race codition that exists between kset_find_obj() and kobject_put(). kset_find_obj() might return kobject that has refcount equal to 0 if this kobject is freeing by kobject_put() in other thread. Here is timeline for the crash in case if kset_find_obj() searches for an object tht nobody holds and other thread is doing kobject_put() on the same kobject: THREAD A (calls kset_find_obj()) THREAD B (calls kobject_put()) splin_lock() atomic_dec_return(kobj->kref), counter gets zero here ... starts kobject cleanup .... spin_lock() // WAIT thread A in kobj_kset_leave() iterate over kset->list atomic_inc(kobj->kref) (counter becomes 1) spin_unlock() spin_lock() // taken // it does not know that thread A increased counter so it remove obj from list spin_unlock() vfree(module) // frees module object with containing kobj // kobj points to freed memory area!! kobject_put(kobj) // OOPS!!!! The race above happens because module.c tries to use kset_find_obj() when somebody unloads module. The module.c code was introduced in commit 6494a93d55fa" Anatol supplied a patch specific for module.c that worked around the problem by simply not using kset_find_obj() at all, but rather than make a local band-aid, this just fixes kset_find_obj() to be thread-safe using the proper model of refusing the get a new reference if the refcount has already dropped to zero. See examples of this proper refcount handling not only in the kref documentation, but in various other equivalent uses of this pattern by grepping for atomic_inc_not_zero(). [ Side note: the module race does indicate that module loading and unloading is not properly serialized wrt sysfs information using the module mutex. That may require further thought, but this is the correct fix at the kobject layer regardless. ] Reported-analyzed-and-tested-by: Anatol Pomozov <anatol.pomozov@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-13 15:15:30 -07:00
kobject: fix kset_find_obj() race with concurrent last kobject_put() Anatol Pomozov identified a race condition that hits module unloading and re-loading. To quote Anatol: "This is a race codition that exists between kset_find_obj() and kobject_put(). kset_find_obj() might return kobject that has refcount equal to 0 if this kobject is freeing by kobject_put() in other thread. Here is timeline for the crash in case if kset_find_obj() searches for an object tht nobody holds and other thread is doing kobject_put() on the same kobject: THREAD A (calls kset_find_obj()) THREAD B (calls kobject_put()) splin_lock() atomic_dec_return(kobj->kref), counter gets zero here ... starts kobject cleanup .... spin_lock() // WAIT thread A in kobj_kset_leave() iterate over kset->list atomic_inc(kobj->kref) (counter becomes 1) spin_unlock() spin_lock() // taken // it does not know that thread A increased counter so it remove obj from list spin_unlock() vfree(module) // frees module object with containing kobj // kobj points to freed memory area!! kobject_put(kobj) // OOPS!!!! The race above happens because module.c tries to use kset_find_obj() when somebody unloads module. The module.c code was introduced in commit 6494a93d55fa" Anatol supplied a patch specific for module.c that worked around the problem by simply not using kset_find_obj() at all, but rather than make a local band-aid, this just fixes kset_find_obj() to be thread-safe using the proper model of refusing the get a new reference if the refcount has already dropped to zero. See examples of this proper refcount handling not only in the kref documentation, but in various other equivalent uses of this pattern by grepping for atomic_inc_not_zero(). [ Side note: the module race does indicate that module loading and unloading is not properly serialized wrt sysfs information using the module mutex. That may require further thought, but this is the correct fix at the kobject layer regardless. ] Reported-analyzed-and-tested-by: Anatol Pomozov <anatol.pomozov@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-13 15:15:30 -07:00
kobject: fix kset_find_obj() race with concurrent last kobject_put() Anatol Pomozov identified a race condition that hits module unloading and re-loading. To quote Anatol: "This is a race codition that exists between kset_find_obj() and kobject_put(). kset_find_obj() might return kobject that has refcount equal to 0 if this kobject is freeing by kobject_put() in other thread. Here is timeline for the crash in case if kset_find_obj() searches for an object tht nobody holds and other thread is doing kobject_put() on the same kobject: THREAD A (calls kset_find_obj()) THREAD B (calls kobject_put()) splin_lock() atomic_dec_return(kobj->kref), counter gets zero here ... starts kobject cleanup .... spin_lock() // WAIT thread A in kobj_kset_leave() iterate over kset->list atomic_inc(kobj->kref) (counter becomes 1) spin_unlock() spin_lock() // taken // it does not know that thread A increased counter so it remove obj from list spin_unlock() vfree(module) // frees module object with containing kobj // kobj points to freed memory area!! kobject_put(kobj) // OOPS!!!! The race above happens because module.c tries to use kset_find_obj() when somebody unloads module. The module.c code was introduced in commit 6494a93d55fa" Anatol supplied a patch specific for module.c that worked around the problem by simply not using kset_find_obj() at all, but rather than make a local band-aid, this just fixes kset_find_obj() to be thread-safe using the proper model of refusing the get a new reference if the refcount has already dropped to zero. See examples of this proper refcount handling not only in the kref documentation, but in various other equivalent uses of this pattern by grepping for atomic_inc_not_zero(). [ Side note: the module race does indicate that module loading and unloading is not properly serialized wrt sysfs information using the module mutex. That may require further thought, but this is the correct fix at the kobject layer regardless. ] Reported-analyzed-and-tested-by: Anatol Pomozov <anatol.pomozov@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-13 15:15:30 -07:00
kobject: fix kset_find_obj() race with concurrent last kobject_put() Anatol Pomozov identified a race condition that hits module unloading and re-loading. To quote Anatol: "This is a race codition that exists between kset_find_obj() and kobject_put(). kset_find_obj() might return kobject that has refcount equal to 0 if this kobject is freeing by kobject_put() in other thread. Here is timeline for the crash in case if kset_find_obj() searches for an object tht nobody holds and other thread is doing kobject_put() on the same kobject: THREAD A (calls kset_find_obj()) THREAD B (calls kobject_put()) splin_lock() atomic_dec_return(kobj->kref), counter gets zero here ... starts kobject cleanup .... spin_lock() // WAIT thread A in kobj_kset_leave() iterate over kset->list atomic_inc(kobj->kref) (counter becomes 1) spin_unlock() spin_lock() // taken // it does not know that thread A increased counter so it remove obj from list spin_unlock() vfree(module) // frees module object with containing kobj // kobj points to freed memory area!! kobject_put(kobj) // OOPS!!!! The race above happens because module.c tries to use kset_find_obj() when somebody unloads module. The module.c code was introduced in commit 6494a93d55fa" Anatol supplied a patch specific for module.c that worked around the problem by simply not using kset_find_obj() at all, but rather than make a local band-aid, this just fixes kset_find_obj() to be thread-safe using the proper model of refusing the get a new reference if the refcount has already dropped to zero. See examples of this proper refcount handling not only in the kref documentation, but in various other equivalent uses of this pattern by grepping for atomic_inc_not_zero(). [ Side note: the module race does indicate that module loading and unloading is not properly serialized wrt sysfs information using the module mutex. That may require further thought, but this is the correct fix at the kobject layer regardless. ] Reported-analyzed-and-tested-by: Anatol Pomozov <anatol.pomozov@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-13 15:15:30 -07:00