CVE-2026-46061: jbd2: fix deadlock in jbd2_journal_cancel_revoke()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-27 · updated 2026-06-17
Weakness: CWE-667

Description

In the Linux kernel, the following vulnerability has been resolved: jbd2: fix deadlock in jbd2_journal_cancel_revoke() Commit f76d4c28a46a ("fs/jbd2: use sleeping version of __find_get_block()") changed jbd2_journal_cancel_revoke() to use __find_get_block_nonatomic() which holds the folio lock instead of i_private_lock. This breaks the lock ordering (folio -> buffer) and causes an ABBA deadlock when the filesystem blocksize < pagesize: T1 T2 ext4_mkdir() ext4_init_new_dir() ext4_append() ext4_getblk() lock_buffer() <- A sync_blockdev() blkdev_writepages() writeback_iter() writeback_get_folio() folio_lock() <- B ext4_journal_get_create_access() jbd2_journal_cancel_revoke() __find_get_block_nonatomic() folio_lock() <- B block_write_full_folio() lock_buffer() <- A This can occasionally cause generic/013 to hang. Fix by only calling __find_get_block_nonatomic() when the passed buffer_head doesn't belong to the bdev, which is the only case that we need to look up its bdev alias. Otherwise, the lookup is redundant since the found buffer_head is equal to the one we passed in.

Affected products

Linux kernel: from 6.12.31 before 6.12.86; from 6.14.9 before 6.15; from 6.15.1 before 6.18.27; from 6.19 before 7.0.4; 6.15, 6.15-rc4, 6.15-rc5, 6.15-rc6, 6.15-rc7 — fixed in 6.12.86, 6.15, 6.18.27, 7.0.4

How to fix

Upgrade to a fixed version: Linux kernel 6.12.86, 6.15, 6.18.27, 7.0.4. Check the vendor advisory for mitigations.

References

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