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a4b732a248
There is a race between cache device register and cache set unregister. For an already registered cache device, register_bcache will call bch_is_open to iterate through all cachesets and check every cache there. The race occurs if cache_set_free executes at the same time and clears the caches right before ca is dereferenced in bch_is_open_cache. To close the race, let's make sure the clean up work is protected by the bch_register_lock as well. This issue can be reproduced as follows, while true; do echo /dev/XXX> /sys/fs/bcache/register ; done& while true; do echo 1> /sys/block/XXX/bcache/set/unregister ; done & and results in the following oops, [ +0.000053] BUG: unable to handle kernel NULL pointer dereference at 0000000000000998 [ +0.000457] #PF error: [normal kernel read fault] [ +0.000464] PGD 800000003ca9d067 P4D 800000003ca9d067 PUD 3ca9c067 PMD 0 [ +0.000388] Oops: 0000 [#1] SMP PTI [ +0.000269] CPU: 1 PID: 3266 Comm: bash Not tainted 5.0.0+ #6 [ +0.000346] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 04/01/2014 [ +0.000472] RIP: 0010:register_bcache+0x1829/0x1990 [bcache] [ +0.000344] Code: b0 48 83 e8 50 48 81 fa e0 e1 10 c0 0f 84 a9 00 00 00 48 89 c6 48 89 ca 0f b7 ba 54 04 00 00 4c 8b 82 60 0c 00 00 85 ff 74 2f <49> 3b a8 98 09 00 00 74 4e 44 8d 47 ff 31 ff 49 c1 e0 03 eb 0d [ +0.000839] RSP: 0018:ffff92ee804cbd88 EFLAGS: 00010202 [ +0.000328] RAX: ffffffffc010e190 RBX: ffff918b5c6b5000 RCX: ffff918b7d8e0000 [ +0.000399] RDX: ffff918b7d8e0000 RSI: ffffffffc010e190 RDI: 0000000000000001 [ +0.000398] RBP: ffff918b7d318340 R08: 0000000000000000 R09: ffffffffb9bd2d7a [ +0.000385] R10: ffff918b7eb253c0 R11: ffffb95980f51200 R12: ffffffffc010e1a0 [ +0.000411] R13: fffffffffffffff2 R14: 000000000000000b R15: ffff918b7e232620 [ +0.000384] FS: 00007f955bec2740(0000) GS:ffff918b7eb00000(0000) knlGS:0000000000000000 [ +0.000420] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ +0.000801] CR2: 0000000000000998 CR3: 000000003cad6000 CR4: 00000000001406e0 [ +0.000837] Call Trace: [ +0.000682] ? _cond_resched+0x10/0x20 [ +0.000691] ? __kmalloc+0x131/0x1b0 [ +0.000710] kernfs_fop_write+0xfa/0x170 [ +0.000733] __vfs_write+0x2e/0x190 [ +0.000688] ? inode_security+0x10/0x30 [ +0.000698] ? selinux_file_permission+0xd2/0x120 [ +0.000752] ? security_file_permission+0x2b/0x100 [ +0.000753] vfs_write+0xa8/0x1a0 [ +0.000676] ksys_write+0x4d/0xb0 [ +0.000699] do_syscall_64+0x3a/0xf0 [ +0.000692] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Liang Chen <liangchen.linux@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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.. | ||
bcache | ||
persistent-data | ||
dm-bio-prison-v1.c | ||
dm-bio-prison-v1.h | ||
dm-bio-prison-v2.c | ||
dm-bio-prison-v2.h | ||
dm-bio-record.h | ||
dm-bufio.c | ||
dm-builtin.c | ||
dm-cache-background-tracker.c | ||
dm-cache-background-tracker.h | ||
dm-cache-block-types.h | ||
dm-cache-metadata.c | ||
dm-cache-metadata.h | ||
dm-cache-policy-internal.h | ||
dm-cache-policy-smq.c | ||
dm-cache-policy.c | ||
dm-cache-policy.h | ||
dm-cache-target.c | ||
dm-core.h | ||
dm-crypt.c | ||
dm-delay.c | ||
dm-era-target.c | ||
dm-exception-store.c | ||
dm-exception-store.h | ||
dm-flakey.c | ||
dm-init.c | ||
dm-integrity.c | ||
dm-io.c | ||
dm-ioctl.c | ||
dm-kcopyd.c | ||
dm-linear.c | ||
dm-log-userspace-base.c | ||
dm-log-userspace-transfer.c | ||
dm-log-userspace-transfer.h | ||
dm-log-writes.c | ||
dm-log.c | ||
dm-mpath.c | ||
dm-mpath.h | ||
dm-path-selector.c | ||
dm-path-selector.h | ||
dm-queue-length.c | ||
dm-raid1.c | ||
dm-raid.c | ||
dm-region-hash.c | ||
dm-round-robin.c | ||
dm-rq.c | ||
dm-rq.h | ||
dm-service-time.c | ||
dm-snap-persistent.c | ||
dm-snap-transient.c | ||
dm-snap.c | ||
dm-stats.c | ||
dm-stats.h | ||
dm-stripe.c | ||
dm-switch.c | ||
dm-sysfs.c | ||
dm-table.c | ||
dm-target.c | ||
dm-thin-metadata.c | ||
dm-thin-metadata.h | ||
dm-thin.c | ||
dm-uevent.c | ||
dm-uevent.h | ||
dm-unstripe.c | ||
dm-verity-fec.c | ||
dm-verity-fec.h | ||
dm-verity-target.c | ||
dm-verity.h | ||
dm-writecache.c | ||
dm-zero.c | ||
dm-zoned-metadata.c | ||
dm-zoned-reclaim.c | ||
dm-zoned-target.c | ||
dm-zoned.h | ||
dm.c | ||
dm.h | ||
Kconfig | ||
Makefile | ||
md-bitmap.c | ||
md-bitmap.h | ||
md-cluster.c | ||
md-cluster.h | ||
md-faulty.c | ||
md-linear.c | ||
md-linear.h | ||
md-multipath.c | ||
md-multipath.h | ||
md.c | ||
md.h | ||
raid0.c | ||
raid0.h | ||
raid1-10.c | ||
raid1.c | ||
raid1.h | ||
raid5-cache.c | ||
raid5-log.h | ||
raid5-ppl.c | ||
raid5.c | ||
raid5.h | ||
raid10.c | ||
raid10.h |