High · published June 25, 2024
In the Linux kernel, the following vulnerability has been resolved:
nilfs2: fix potential kernel bug due to lack of writeback flag waiting
Destructive writes to a block device on which nilfs2 is mounted can cause
a kernel bug in the folio/page writeback start routine or writeback end
routine (__folio_start_writeback in the log below):
kernel BUG at mm/page-writeback.c:3070!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
...
RIP: 0010:__folio_start_writeback+0xbaa/0x10e0
Code: 25 ff 0f 00 00 0f 84 18 01 00 00 e8 40 ca c6 ff e9 17 f6 ff ff
e8 36 ca c6 ff 4c 89 f7 48 c7 c6 80 c0 12 84 e8 e7 b3 0f 00 90 <0f>
0b e8 1f ca c6 ff 4c 89 f7 48 c7 c6 a0 c6 12 84 e8 d0 b3 0f 00
...
Call Trace:
<TASK>
nilfs_segctor_do_construct+0x4654/0x69d0 [nilfs2]
nilfs_segctor_construct+0x181/0x6b0 [nilfs2]
nilfs_segctor_thread+0x548/0x11c0 [nilfs2]
kthread+0x2f0/0x390
ret_from_fork+0x4b/0x80
ret_from_fork_asm+0x1a/0x30
</TASK>
This is because when the log writer starts a writeback for segment summary
blocks or a super root block that use the backing device's page cache, it
does not wait for the ongoing folio/page writeback, resulting in an
inconsistent writeback state.
Fix this issue by waiting for ongoing writebacks when putting
folios/pages on the backing device into writeback state.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 2.6.30, < 4.19.317 | 4.19.317 |
| linux/linux_kernel | ≥ 4.20, < 5.4.279 | 5.4.279 |
| linux/linux_kernel | ≥ 5.5, < 5.10.221 | 5.10.221 |
| linux/linux_kernel | ≥ 5.11, < 5.15.162 | 5.15.162 |
| linux/linux_kernel | ≥ 5.16, < 6.1.95 | 6.1.95 |
| linux/linux_kernel | ≥ 6.2, < 6.6.35 | 6.6.35 |
| linux/linux_kernel | ≥ 6.7, < 6.9.5 | 6.9.5 |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |