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linux/drivers/mtd/ubi
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Bradley Bolen 7f29ae9f97 ubi: block: Fix locking for idr_alloc/idr_remove 
This fixes a race with idr_alloc where gd->first_minor can be set to the
same value for two simultaneous calls to ubiblock_create.  Each instance
calls device_add_disk with the same first_minor.  device_add_disk calls
bdi_register_owner which generates several warnings.

WARNING: CPU: 1 PID: 179 at kernel-source/fs/sysfs/dir.c:31
sysfs_warn_dup+0x68/0x88
sysfs: cannot create duplicate filename '/devices/virtual/bdi/252:2'

WARNING: CPU: 1 PID: 179 at kernel-source/lib/kobject.c:240
kobject_add_internal+0x1ec/0x2f8
kobject_add_internal failed for 252:2 with -EEXIST, don't try to
register things with the same name in the same directory

WARNING: CPU: 1 PID: 179 at kernel-source/fs/sysfs/dir.c:31
sysfs_warn_dup+0x68/0x88
sysfs: cannot create duplicate filename '/dev/block/252:2'

However, device_add_disk does not error out when bdi_register_owner
returns an error.  Control continues until reaching blk_register_queue.
It then BUGs.

kernel BUG at kernel-source/fs/sysfs/group.c:113!
[<c01e26cc>] (internal_create_group) from [<c01e2950>]
(sysfs_create_group+0x20/0x24)
[<c01e2950>] (sysfs_create_group) from [<c00e3d38>]
(blk_trace_init_sysfs+0x18/0x20)
[<c00e3d38>] (blk_trace_init_sysfs) from [<c02bdfbc>]
(blk_register_queue+0xd8/0x154)
[<c02bdfbc>] (blk_register_queue) from [<c02cec84>]
(device_add_disk+0x194/0x44c)
[<c02cec84>] (device_add_disk) from [<c0436ec8>]
(ubiblock_create+0x284/0x2e0)
[<c0436ec8>] (ubiblock_create) from [<c0427bb8>]
(vol_cdev_ioctl+0x450/0x554)
[<c0427bb8>] (vol_cdev_ioctl) from [<c0189110>] (vfs_ioctl+0x30/0x44)
[<c0189110>] (vfs_ioctl) from [<c01892e0>] (do_vfs_ioctl+0xa0/0x790)
[<c01892e0>] (do_vfs_ioctl) from [<c0189a14>] (SyS_ioctl+0x44/0x68)
[<c0189a14>] (SyS_ioctl) from [<c0010640>] (ret_fast_syscall+0x0/0x34)

Locking idr_alloc/idr_remove removes the race and keeps gd->first_minor
unique.

Fixes: 2bf50d42f3 ("UBI: block: Dynamically allocate minor numbers")
Cc: stable@vger.kernel.org
Signed-off-by: Bradley Bolen <bradleybolen@gmail.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2018-01-18 16:48:31 +01:00
..
attach.c UBI: introduce the VID buffer concept 2016-10-02 22:48:14 +02:00
block.c ubi: block: Fix locking for idr_alloc/idr_remove 2018-01-18 16:48:31 +01:00
build.c mtd: ubi: Use 'max_bad_blocks' to compute bad_peb_limit if available 2018-01-17 19:28:54 +01:00
cdev.c UBI: add an helper to check lnum validity 2016-10-02 22:48:14 +02:00
debug.c ubi: Add debugfs file for tracking PEB state 2017-05-08 20:49:02 +02:00
debug.h
eba.c ubi: Fix copy/paste error in function documentation 2018-01-18 00:18:51 +01:00
fastmap-wl.c ubi: Fastmap: Fix typo 2018-01-18 00:18:50 +01:00
fastmap.c ubi: fastmap: Clean up the initialization of pointer p 2018-01-17 21:48:02 +01:00
gluebi.c ubi: gluebi: Fix double refcounting 2016-07-29 23:31:54 +02:00
io.c UBI: Fix typos 2017-03-24 15:33:32 +01:00
kapi.c statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00
Kconfig UBI: Fix typos 2017-03-24 15:33:32 +01:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
misc.c mtd: ubi: Add logging functions ubi_msg, ubi_warn and ubi_err 2016-03-20 21:36:05 +01:00
ubi-media.h UBI: Fix two typos in comments 2017-09-13 22:05:30 +02:00
ubi.h UBI: Fix typos 2017-03-24 15:33:32 +01:00
upd.c ubi/upd: Always flush after prepared for an update 2017-03-30 09:27:11 +02:00
vmt.c ubi: Fix race condition between ubi volume creation and udev 2018-01-17 21:47:33 +01:00
vtbl.c UBI: introduce the VID buffer concept 2016-10-02 22:48:14 +02:00
wl.c mtd: ubi: wl: Fix error return code in ubi_wl_init() 2018-01-18 16:45:19 +01:00
wl.h ubi: Fastmap: Fix typo 2018-01-18 00:18:50 +01:00