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Zhiqiang Liu a9e60cba99 brd: check and limit max_part par 
[ Upstream commit c8ab422553 ]

In brd_init func, rd_nr num of brd_device are firstly allocated
and add in brd_devices, then brd_devices are traversed to add each
brd_device by calling add_disk func. When allocating brd_device,
the disk->first_minor is set to i * max_part, if rd_nr * max_part
is larger than MINORMASK, two different brd_device may have the same
devt, then only one of them can be successfully added.
when rmmod brd.ko, it will cause oops when calling brd_exit.

Follow those steps:
  # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576
  # rmmod brd
then, the oops will appear.

Oops log:
[  726.613722] Call trace:
[  726.614175]  kernfs_find_ns+0x24/0x130
[  726.614852]  kernfs_find_and_get_ns+0x44/0x68
[  726.615749]  sysfs_remove_group+0x38/0xb0
[  726.616520]  blk_trace_remove_sysfs+0x1c/0x28
[  726.617320]  blk_unregister_queue+0x98/0x100
[  726.618105]  del_gendisk+0x144/0x2b8
[  726.618759]  brd_exit+0x68/0x560 [brd]
[  726.619501]  __arm64_sys_delete_module+0x19c/0x2a0
[  726.620384]  el0_svc_common+0x78/0x130
[  726.621057]  el0_svc_handler+0x38/0x78
[  726.621738]  el0_svc+0x8/0xc
[  726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260)

Here, we add brd_check_and_reset_par func to check and limit max_part par.

--
V5->V6:
 - remove useless code

V4->V5:(suggested by Ming Lei)
 - make sure max_part is not larger than DISK_MAX_PARTS

V3->V4:(suggested by Ming Lei)
 - remove useless change
 - add one limit of max_part

V2->V3: (suggested by Ming Lei)
 - clear .minors when running out of consecutive minor space in brd_alloc
 - remove limit of rd_nr

V1->V2:
 - add more checks in brd_check_par_valid as suggested by Ming Lei.

Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2020-02-24 08:38:49 +01:00
arch microblaze: Prevent the overflow of the start 2020-02-24 08:38:49 +01:00
block block, bfq: do not plug I/O for bfq_queues with no proc refs 2020-02-24 08:38:09 +01:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto crypto: essiv - fix AEAD capitalization and preposition use in help text 2020-02-24 08:38:32 +01:00
Documentation fbdev: fix numbering of fbcon options 2020-02-24 08:38:21 +01:00
drivers brd: check and limit max_part par 2020-02-24 08:38:49 +01:00
fs reiserfs: prevent NULL pointer dereference in reiserfs_insert_item() 2020-02-24 08:38:47 +01:00
include raid6/test: fix a compilation warning 2020-02-24 08:38:27 +01:00
init Revert "um: Enable CONFIG_CONSTRUCTORS" 2020-02-01 09:33:00 +00:00
ipc ipc/msg.c: consolidate all xxxctl_down() functions 2020-02-11 04:36:39 -08:00
kernel tracing: Fix now invalid var_ref_vals assumption in trace action 2020-02-24 08:38:47 +01:00
lib lib/scatterlist.c: adjust indentation in __sg_alloc_table 2020-02-24 08:38:47 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush 2020-02-11 04:37:14 -08:00
net sunrpc: Fix potential leaks in sunrpc_cache_unhash() 2020-02-24 08:38:40 +01:00
samples samples/bpf: Set -fno-stack-protector when building BPF programs 2020-02-24 08:38:15 +01:00
scripts bpf, btf: Always output invariant hit in pahole DWARF to BTF transform 2020-02-24 08:38:40 +01:00
security selinux: ensure we cleanup the internal AVC counters on error in avc_update() 2020-02-24 08:38:19 +01:00
sound ASoC: Intel: consistent HDMI codec probing code 2020-02-24 08:38:45 +01:00
tools tc-testing: add missing 'nsPlugin' to basic.json 2020-02-24 08:38:49 +01:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt KVM: arm64: Treat emulated TVAL TimerValue as a signed 32-bit integer 2020-02-14 16:53:04 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap MAINTAINERS: update my email address 2020-01-11 14:33:39 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: correct entries for ISDN/mISDN section 2020-02-11 04:36:38 -08:00
Makefile Linux 5.5.5 2020-02-19 19:54:14 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.