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CVE-2026-74321

btrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs()

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs() In the beginning of the loop, we try to obtain a locked delayed ref head, if 'locked_ref' is currently NULL, by calling btrfs_select_ref_head(), which can return an error pointer. If the error pointer is -EAGAIN we do a continue and go back to the beginning of the loop, which will not try again to call btrfs_select_ref_head() since 'locked_ref' is no longer NULL but it's ERR_PTR(-EAGAIN), and then we do: spin_lock(&locked_ref->lock); against a ERR_PTR(-EAGAIN) value, generating an invalid pointer dereference. Fix this by ensuring that 'locked_ref' is set to NULL when btrfs_select_ref_head() returns ERR_PTR(-EAGAIN) and incrementing 'count' as well, to prevent infinite looping. We do this by doing a goto to the bottom of the loop that already sets 'locked_ref' to NULL and does a cond_resched(), with an increment to 'count' right before the goto. These measures were in place before the refactoring in commit 0110a4c43451 ("btrfs: refactor __btrfs_run_delayed_refs loop") but were unintentionally lost afterwards.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • Linux Linux

    From 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 · fixed in c372ca227e16bace86f1df1fa4ae6849e2fcfa28; From 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 · fixed in a71143590ce9764dbcb47617647592ff8b4d48bc; From 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 · fixed in 65770111a2d47c2b15e20b2ba92bb12198f289d4; From 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 · fixed in 015dc4a1e0c2cba551d4620eba13d26d5081dc34; From 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 · fixed in ba9fa2ff5981589bb49094d3358c339b37c47f53; From 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 · fixed in 3b15d02be05e74321adb1e0ae0cb4ccfba7c6cb1; From 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 · fixed in 9faa6b69ad73f03c7bde53e07d75a28822dc9a1a; From 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 · fixed in 486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae

  • Linux Linux

    4.20

  • KernelLinux

    From 4.20.0 · fixed in 5.10.261; From 5.11.0 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.178; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.5

References 8

git.kernel.org