Description
In the Linux kernel, the following vulnerability has been resolved: dm thin: Use last transaction's pmd->root when commit failed Recently we found a softlock up problem in dm thin pool btree lookup code due to corrupted metadata: Kernel panic - not syncing: softlockup: hung tasks CPU: 7 PID: 2669225 Comm: kworker/u16:3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Workqueue: dm-thin do_worker [dm_thin_pool] Call Trace: <IRQ> dump_stack+0x9c/0xd3 panic+0x35d/0x6b9 watchdog_timer_fn.cold+0x16/0x25 __run_hrtimer+0xa2/0x2d0 </IRQ> RIP: 0010:__relink_lru+0x102/0x220 [dm_bufio] __bufio_new+0x11f/0x4f0 [dm_bufio] new_read+0xa3/0x1e0 [dm_bufio] dm_bm_read_lock+0x33/0xd0 [dm_persistent_data] ro_step+0x63/0x100 [dm_persistent_data] btree_lookup_raw.constprop.0+0x44/0x220 [dm_persistent_data] dm_btree_lookup+0x16f/0x210 [dm_persistent_data] dm_thin_find_block+0x12c/0x210 [dm_thin_pool] __process_bio_read_only+0xc5/0x400 [dm_thin_pool] process_thin_deferred_bios+0x1a4/0x4a0 [dm_thin_pool] process_one_work+0x3c5/0x730 Following process may generate a broken btree mixed with fresh and stale btree nodes, which could get dm thin trapped in an infinite loop while looking up data block: Transaction 1: pmd->root = A, A->B->C // One path in btree pmd->root = X, X->Y->Z // Copy-up Transaction 2: X,Z is updated on disk, Y write failed. // Commit failed, dm thin becomes read-only. process_bio_read_only dm_thin_find_block __find_block dm_btree_lookup(pmd->root) The pmd->root points to a broken btree, Y may contain stale node pointing to any block, for example X, which gets dm thin trapped into a dead loop while looking up Z. Fix this by setting pmd->root in __open_metadata(), so that dm thin will use the last transaction's pmd->root if commit failed. Fetch a reproducer in [Link]. Linke: https://bugzilla.kernel.org/show_bug.cgi?id=216790
Product status
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before b35a22760aa5008d82533e59b0f0b5eb1b02d4e5
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before 87d69b8824ca9b090f5a8ed47f758e8f6eecb871
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before 3db757ffdd87ed8d7118b2250236a496502a660f
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before f758987ff0af3a4b5ee69e95cab6a5294e4367b0
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before 94f01ecc2aa0be992865acc80ebb6701f731f955
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before 4b710e8481ade7c9200e94d3018e99dc42a0a0e8
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before a63ce4eca86fd207e3db07c00fb7ccf4adf1b230
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before b91f481300e3a10eaf66b94fc39b740928762aaf
991d9fa02da0dd1f843dc011376965e0c8c6c9b5 before 7991dbff6849f67e823b7cc0c15e5a90b0549b9f
3.2
Any version before 3.2
4.9.337
4.14.303
4.19.270
5.4.229
5.10.163
5.15.87
6.0.18
6.1.4
6.2
References
git.kernel.org/...c/b35a22760aa5008d82533e59b0f0b5eb1b02d4e5
git.kernel.org/...c/87d69b8824ca9b090f5a8ed47f758e8f6eecb871
git.kernel.org/...c/3db757ffdd87ed8d7118b2250236a496502a660f
git.kernel.org/...c/f758987ff0af3a4b5ee69e95cab6a5294e4367b0
git.kernel.org/...c/94f01ecc2aa0be992865acc80ebb6701f731f955
git.kernel.org/...c/4b710e8481ade7c9200e94d3018e99dc42a0a0e8
git.kernel.org/...c/a63ce4eca86fd207e3db07c00fb7ccf4adf1b230
git.kernel.org/...c/b91f481300e3a10eaf66b94fc39b740928762aaf
git.kernel.org/...c/7991dbff6849f67e823b7cc0c15e5a90b0549b9f
