linux/drivers/virtio/virtio.c

752 lines
19 KiB

virtio: acknowledge all features before access The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db79 ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang <jasowang@redhat.com> Cc: stable@vger.kernel.org Fixes: 404123c2db79 ("virtio: allow drivers to validate features") Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" <pasic@linux.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-01-14 14:58:41 -05:00
virtio: harden vring IRQ This is a rework on the previous IRQ hardening that is done for virtio-pci where several drawbacks were found and were reverted: 1) try to use IRQF_NO_AUTOEN which is not friendly to affinity managed IRQ that is used by some device such as virtio-blk 2) done only for PCI transport The vq->broken is re-used in this patch for implementing the IRQ hardening. The vq->broken is set to true during both initialization and reset. And the vq->broken is set to false in virtio_device_ready(). Then vring_interrupt() can check and return when vq->broken is true. And in this case, switch to return IRQ_NONE to let the interrupt core aware of such invalid interrupt to prevent IRQ storm. The reason of using a per queue variable instead of a per device one is that we may need it for per queue reset hardening in the future. Note that the hardening is only done for vring interrupt since the config interrupt hardening is already done in commit 22b7050a024d7 ("virtio: defer config changed notifications"). But the method that is used by config interrupt can't be reused by the vring interrupt handler because it uses spinlock to do the synchronization which is expensive. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Halil Pasic <pasic@linux.ibm.com> Cc: Cornelia Huck <cohuck@redhat.com> Cc: Vineeth Vijayan <vneethv@linux.ibm.com> Cc: Peter Oberparleiter <oberpar@linux.ibm.com> Cc: linux-s390@vger.kernel.org Signed-off-by: Jason Wang <jasowang@redhat.com> Message-Id: <20220527060120.20964-9-jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
2022-05-27 14:01:19 +08:00
virtio: harden vring IRQ This is a rework on the previous IRQ hardening that is done for virtio-pci where several drawbacks were found and were reverted: 1) try to use IRQF_NO_AUTOEN which is not friendly to affinity managed IRQ that is used by some device such as virtio-blk 2) done only for PCI transport The vq->broken is re-used in this patch for implementing the IRQ hardening. The vq->broken is set to true during both initialization and reset. And the vq->broken is set to false in virtio_device_ready(). Then vring_interrupt() can check and return when vq->broken is true. And in this case, switch to return IRQ_NONE to let the interrupt core aware of such invalid interrupt to prevent IRQ storm. The reason of using a per queue variable instead of a per device one is that we may need it for per queue reset hardening in the future. Note that the hardening is only done for vring interrupt since the config interrupt hardening is already done in commit 22b7050a024d7 ("virtio: defer config changed notifications"). But the method that is used by config interrupt can't be reused by the vring interrupt handler because it uses spinlock to do the synchronization which is expensive. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Halil Pasic <pasic@linux.ibm.com> Cc: Cornelia Huck <cohuck@redhat.com> Cc: Vineeth Vijayan <vneethv@linux.ibm.com> Cc: Peter Oberparleiter <oberpar@linux.ibm.com> Cc: linux-s390@vger.kernel.org Signed-off-by: Jason Wang <jasowang@redhat.com> Message-Id: <20220527060120.20964-9-jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
2022-05-27 14:01:19 +08:00
virtio: acknowledge all features before access The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db79 ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang <jasowang@redhat.com> Cc: stable@vger.kernel.org Fixes: 404123c2db79 ("virtio: allow drivers to validate features") Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" <pasic@linux.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-01-14 14:58:41 -05:00
virtio: acknowledge all features before access The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db79 ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang <jasowang@redhat.com> Cc: stable@vger.kernel.org Fixes: 404123c2db79 ("virtio: allow drivers to validate features") Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" <pasic@linux.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-01-14 14:58:41 -05:00
virtio: acknowledge all features before access The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db79 ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang <jasowang@redhat.com> Cc: stable@vger.kernel.org Fixes: 404123c2db79 ("virtio: allow drivers to validate features") Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" <pasic@linux.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-01-14 14:58:41 -05:00
virtio: acknowledge all features before access The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db79 ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang <jasowang@redhat.com> Cc: stable@vger.kernel.org Fixes: 404123c2db79 ("virtio: allow drivers to validate features") Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" <pasic@linux.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-01-14 14:58:41 -05:00
virtio: acknowledge all features before access The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db79 ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang <jasowang@redhat.com> Cc: stable@vger.kernel.org Fixes: 404123c2db79 ("virtio: allow drivers to validate features") Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" <pasic@linux.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-01-14 14:58:41 -05:00
bus: Make remove callback return void The driver core ignores the return value of this callback because there is only little it can do when a device disappears. This is the final bit of a long lasting cleanup quest where several buses were converted to also return void from their remove callback. Additionally some resource leaks were fixed that were caused by drivers returning an error code in the expectation that the driver won't go away. With struct bus_type::remove returning void it's prevented that newly implemented buses return an ignored error code and so don't anticipate wrong expectations for driver authors. Reviewed-by: Tom Rix <trix@redhat.com> (For fpga) Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Reviewed-by: Cornelia Huck <cohuck@redhat.com> (For drivers/s390 and drivers/vfio) Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> (For ARM, Amba and related parts) Acked-by: Mark Brown <broonie@kernel.org> Acked-by: Chen-Yu Tsai <wens@csie.org> (for sunxi-rsb) Acked-by: Pali Rohár <pali@kernel.org> Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org> (for media) Acked-by: Hans de Goede <hdegoede@redhat.com> (For drivers/platform) Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Acked-By: Vinod Koul <vkoul@kernel.org> Acked-by: Juergen Gross <jgross@suse.com> (For xen) Acked-by: Lee Jones <lee.jones@linaro.org> (For mfd) Acked-by: Johannes Thumshirn <jth@kernel.org> (For mcb) Acked-by: Johan Hovold <johan@kernel.org> Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> (For slimbus) Acked-by: Kirti Wankhede <kwankhede@nvidia.com> (For vfio) Acked-by: Maximilian Luz <luzmaximilian@gmail.com> Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> (For ulpi and typec) Acked-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com> (For ipack) Acked-by: Geoff Levand <geoff@infradead.org> (For ps3) Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com> (For thunderbolt) Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> (For intel_th) Acked-by: Dominik Brodowski <linux@dominikbrodowski.net> (For pcmcia) Acked-by: Rafael J. Wysocki <rafael@kernel.org> (For ACPI) Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org> (rpmsg and apr) Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> (For intel-ish-hid) Acked-by: Dan Williams <dan.j.williams@intel.com> (For CXL, DAX, and NVDIMM) Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com> (For isa) Acked-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (For firewire) Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> (For hid) Acked-by: Thorsten Scherer <t.scherer@eckelmann.de> (For siox) Acked-by: Sven Van Asbroeck <TheSven73@gmail.com> (For anybuss) Acked-by: Ulf Hansson <ulf.hansson@linaro.org> (For MMC) Acked-by: Wolfram Sang <wsa@kernel.org> # for I2C Acked-by: Sudeep Holla <sudeep.holla@arm.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Acked-by: Finn Thain <fthain@linux-m68k.org> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20210713193522.1770306-6-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-13 21:35:22 +02:00
virtgpu: don't reset on shutdown It looks like GPUs are used after shutdown is invoked. Thus, breaking virtio gpu in the shutdown callback is not a good idea - guest hangs attempting to finish console drawing, with these warnings: [ 20.504464] WARNING: CPU: 0 PID: 568 at drivers/gpu/drm/virtio/virtgpu_vq.c:358 virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.505685] Modules linked in: nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 rfkill ip_set nf_tables nfnetlink vfat fat intel_rapl_msr intel_rapl_common intel_uncore_frequency_common nfit libnvdimm kvm_intel kvm rapl iTCO_wdt iTCO_vendor_support virtio_gpu virtio_dma_buf pcspkr drm_shmem_helper i2c_i801 drm_kms_helper lpc_ich i2c_smbus virtio_balloon joydev drm fuse xfs libcrc32c ahci libahci crct10dif_pclmul crc32_pclmul crc32c_intel libata virtio_net ghash_clmulni_intel net_failover virtio_blk failover serio_raw dm_mirror dm_region_hash dm_log dm_mod [ 20.511847] CPU: 0 PID: 568 Comm: kworker/0:3 Kdump: loaded Tainted: G W ------- --- 5.14.0-578.6675_1757216455.el9.x86_64 #1 [ 20.513157] Hardware name: Red Hat KVM/RHEL, BIOS edk2-20241117-3.el9 11/17/2024 [ 20.513918] Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] [ 20.514626] RIP: 0010:virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.515332] Code: 00 00 48 85 c0 74 0c 48 8b 78 08 48 89 ee e8 51 50 00 00 65 ff 0d 42 e3 74 3f 0f 85 69 ff ff ff 0f 1f 44 00 00 e9 5f ff ff ff <0f> 0b e9 3f ff ff ff 48 83 3c 24 00 74 0e 49 8b 7f 40 48 85 ff 74 [ 20.517272] RSP: 0018:ff34f0a8c0787ad8 EFLAGS: 00010282 [ 20.517820] RAX: 00000000fffffffb RBX: 0000000000000000 RCX: 0000000000000820 [ 20.518565] RDX: 0000000000000000 RSI: ff34f0a8c0787be0 RDI: ff218bef03a26300 [ 20.519308] RBP: ff218bef03a26300 R08: 0000000000000001 R09: ff218bef07224360 [ 20.520059] R10: 0000000000008dc0 R11: 0000000000000002 R12: ff218bef02630028 [ 20.520806] R13: ff218bef0263fb48 R14: ff218bef00cb8000 R15: ff218bef07224360 [ 20.521555] FS: 0000000000000000(0000) GS:ff218bef7ba00000(0000) knlGS:0000000000000000 [ 20.522397] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 20.522996] CR2: 000055ac4f7871c0 CR3: 000000010b9f2002 CR4: 0000000000771ef0 [ 20.523740] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 20.524477] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 [ 20.525223] PKRU: 55555554 [ 20.525515] Call Trace: [ 20.525777] <TASK> [ 20.526003] ? show_trace_log_lvl+0x1c4/0x2df [ 20.526464] ? show_trace_log_lvl+0x1c4/0x2df [ 20.526925] ? virtio_gpu_queue_fenced_ctrl_buffer+0x82/0x2c0 [virtio_gpu] [ 20.527643] ? virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.528282] ? __warn+0x7e/0xd0 [ 20.528621] ? virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.529256] ? report_bug+0x100/0x140 [ 20.529643] ? handle_bug+0x3c/0x70 [ 20.530010] ? exc_invalid_op+0x14/0x70 [ 20.530421] ? asm_exc_invalid_op+0x16/0x20 [ 20.530862] ? virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.531506] ? virtio_gpu_queue_ctrl_sgs+0x174/0x290 [virtio_gpu] [ 20.532148] virtio_gpu_queue_fenced_ctrl_buffer+0x82/0x2c0 [virtio_gpu] [ 20.532843] virtio_gpu_primary_plane_update+0x3e2/0x460 [virtio_gpu] [ 20.533520] drm_atomic_helper_commit_planes+0x108/0x320 [drm_kms_helper] [ 20.534233] drm_atomic_helper_commit_tail+0x45/0x80 [drm_kms_helper] [ 20.534914] commit_tail+0xd2/0x130 [drm_kms_helper] [ 20.535446] drm_atomic_helper_commit+0x11b/0x140 [drm_kms_helper] [ 20.536097] drm_atomic_commit+0xa4/0xe0 [drm] [ 20.536588] ? __pfx___drm_printfn_info+0x10/0x10 [drm] [ 20.537162] drm_atomic_helper_dirtyfb+0x192/0x270 [drm_kms_helper] [ 20.537823] drm_fbdev_shmem_helper_fb_dirty+0x43/0xa0 [drm_shmem_helper] [ 20.538536] drm_fb_helper_damage_work+0x87/0x160 [drm_kms_helper] [ 20.539188] process_one_work+0x194/0x380 [ 20.539612] worker_thread+0x2fe/0x410 [ 20.540007] ? __pfx_worker_thread+0x10/0x10 [ 20.540456] kthread+0xdd/0x100 [ 20.540791] ? __pfx_kthread+0x10/0x10 [ 20.541190] ret_from_fork+0x29/0x50 [ 20.541566] </TASK> [ 20.541802] ---[ end trace 0000000000000000 ]--- It looks like the shutdown is called in the middle of console drawing, so we should either wait for it to finish, or let drm handle the shutdown. This patch implements this second option: Add an option for drivers to bypass the common break+reset handling. As DRM is careful to flush/synchronize outstanding buffers, it looks like GPU can just have a NOP there. Reviewed-by: Eric Auger <eric.auger@redhat.com> Tested-by: Eric Auger <eric.auger@redhat.com> Fixes: 8bd2fa086a04 ("virtio: break and reset virtio devices on device_shutdown()") Cc: Eric Auger <eauger@redhat.com> Cc: Jocelyn Falempe <jfalempe@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Message-Id: <8490dbeb6f79ed039e6c11d121002618972538a3.1744293540.git.mst@redhat.com>
2025-04-10 03:16:26 -04:00
virtio: harden vring IRQ This is a rework on the previous IRQ hardening that is done for virtio-pci where several drawbacks were found and were reverted: 1) try to use IRQF_NO_AUTOEN which is not friendly to affinity managed IRQ that is used by some device such as virtio-blk 2) done only for PCI transport The vq->broken is re-used in this patch for implementing the IRQ hardening. The vq->broken is set to true during both initialization and reset. And the vq->broken is set to false in virtio_device_ready(). Then vring_interrupt() can check and return when vq->broken is true. And in this case, switch to return IRQ_NONE to let the interrupt core aware of such invalid interrupt to prevent IRQ storm. The reason of using a per queue variable instead of a per device one is that we may need it for per queue reset hardening in the future. Note that the hardening is only done for vring interrupt since the config interrupt hardening is already done in commit 22b7050a024d7 ("virtio: defer config changed notifications"). But the method that is used by config interrupt can't be reused by the vring interrupt handler because it uses spinlock to do the synchronization which is expensive. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Halil Pasic <pasic@linux.ibm.com> Cc: Cornelia Huck <cohuck@redhat.com> Cc: Vineeth Vijayan <vneethv@linux.ibm.com> Cc: Peter Oberparleiter <oberpar@linux.ibm.com> Cc: linux-s390@vger.kernel.org Signed-off-by: Jason Wang <jasowang@redhat.com> Message-Id: <20220527060120.20964-9-jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
2022-05-27 14:01:19 +08:00
virtio: fix use-after-free in unregister_virtio_device() device_unregister() is device_del() plus put_device(). When the caller holds no extra reference, that drops the last one and runs the release callback, which for several transports frees the memory the embedded struct virtio_device sits in. unregister_virtio_device() then calls virtio_debug_device_exit(), which reads dev->debugfs_dir out of the freed object. Affected transports are the ones whose release callback frees and whose remove path takes no reference: virtio_mmio, virtio_vdpa, virtio_uml, mlxbf-tmfifo and virtio_ccw. virtio_pci is unaffected because virtio_pci_remove() brackets the call with get_device() and put_device(). Remove the debugfs entries before the device can go away. They are only accessed through the protected debugfs interface, so debugfs_remove_recursive() waits for in-progress file operations before returning. Tearing them down while the device is still alive is therefore safe. Reproduced on User-Mode Linux with CONFIG_KASAN and CONFIG_VIRTIO_DEBUG by unbinding a virtio-uml device: BUG: KASAN: slab-use-after-free in virtio_debug_device_exit+0x36/0x4d Read of size 8 at addr 00000000616e0b10 by task init/1 __asan_report_load8_noabort virtio_debug_device_exit+0x36/0x4d unregister_virtio_device+0x48/0x75 virtio_uml_remove platform_remove device_release_driver_internal unbind_store Freed by task 1: kfree virtio_uml_release_dev device_release kobject_put put_device device_unregister With this applied, the report is gone and unbind is clean. Fixes: 96a8326d69ff ("virtio: add debugfs infrastructure to allow to debug virtio features") Assisted-by: Claude:claude-opus-5 Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Message-ID: <20260821213953.76906-1-kmehltretter@gmail.com>
2026-08-21 23:39:53 +02:00
virtio: acknowledge all features before access The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db79 ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang <jasowang@redhat.com> Cc: stable@vger.kernel.org Fixes: 404123c2db79 ("virtio: allow drivers to validate features") Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" <pasic@linux.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-01-14 14:58:41 -05:00