CVE-2025-71184: btrfs: fix NULL dereference on root when tracing inode eviction

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: 2026-01-31 · updated 2026-10-30
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix NULL dereference on root when tracing inode eviction When evicting an inode the first thing we do is to setup tracing for it, which implies fetching the root's id. But in btrfs_evict_inode() the root might be NULL, as implied in the next check that we do in btrfs_evict_inode(). Hence, we either should set the ->root_objectid to 0 in case the root is NULL, or we move tracing setup after checking that the root is not NULL. Setting the rootid to 0 at least gives us the possibility to trace this call even in the case when the root is NULL, so that's the solution taken here.

Affected products

Linux kernel: from 2.6.39.1 before 6.6.130; from 6.7 before 6.12.66; from 6.13 before 6.18.6; 6.19-rc1, 6.19-rc2, 6.19-rc3, 6.19-rc4, 6.19-rc5, 6.19-rc6 (+2); 2.6.39 — fixed in 6.6.130, 6.12.66, 6.18.6
Linux: 2.6.39 — fixed in 6.19

How to fix

Upgrade to a fixed version: Linux kernel 6.6.130, 6.12.66, 6.18.6; Linux 6.19. Check the vendor advisory for mitigations.

References

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