CVE-2024-26685: nilfs2: fix potential bug in end_buffer_async_write
First published: Wed Apr 03 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential bug in end_buffer_async_write According to a syzbot report, end_buffer_async_write(), which handles the completion of block device writes, may detect abnormal condition of the buffer async_write flag and cause a BUG_ON failure when using nilfs2. Nilfs2 itself does not use end_buffer_async_write(). But, the async_write flag is now used as a marker by commit 7f42ec394156 ("nilfs2: fix issue with race condition of competition between segments for dirty blocks") as a means of resolving double list insertion of dirty blocks in nilfs_lookup_dirty_data_buffers() and nilfs_lookup_node_buffers() and the resulting crash. This modification is safe as long as it is used for file data and b-tree node blocks where the page caches are independent. However, it was irrelevant and redundant to also introduce async_write for segment summary and super root blocks that share buffers with the backing device. This led to the possibility that the BUG_ON check in end_buffer_async_write would fail as described above, if independent writebacks of the backing device occurred in parallel. The use of async_write for segment summary buffers has already been removed in a previous change. Fix this issue by removing the manipulation of the async_write flag for the remaining super root block buffer.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.112-1 6.11.7-1 6.11.9-1 |
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Reference Links
- https://git.kernel.org/stable/c/2c3bdba00283a6c7a5b19481a59a730f46063803
- https://git.kernel.org/stable/c/5bc09b397cbf1221f8a8aacb1152650c9195b02b
- https://git.kernel.org/stable/c/626daab3811b772086aef1bf8eed3ffe6f523eff
- https://git.kernel.org/stable/c/6589f0f72f8edd1fa11adce4eedbd3615f2e78ab
- https://git.kernel.org/stable/c/8fa90634ec3e9cc50f42dd605eec60f2d146ced8
- https://git.kernel.org/stable/c/c4a09fdac625e64abe478dcf88bfa20406616928
- https://git.kernel.org/stable/c/d31c8721e816eff5ca6573cc487754f357c093cd
- https://git.kernel.org/stable/c/f3e4963566f58726d3265a727116a42b591f6596
- https://launchpad.net/bugs/cve/CVE-2024-26685
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-26685
- https://nvd.nist.gov/vuln/detail/CVE-2024-26685
- https://security-tracker.debian.org/tracker/CVE-2024-26685
- https://ubuntu.com/security/CVE-2024-26685
- https://git.kernel.org/linus/5bc09b397cbf1221f8a8aacb1152650c9195b02b
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