CVE-2026-93798

btrfs: fix reloc root cleanup in merge_reloc_roots()

State: Published
Severity: 7.8 High
Published: Sep 24, 2026
Updated: Oct 3, 2026
Reserved: Sep 18, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

btrfs: fix reloc root cleanup in merge_reloc_roots()

If the root we got has zero root refs in its root item, we are resetting the root's ->reloc_root without using barriers like we do everywhere else. Sashiko complained about this while reviewing another patch, and it's correct (see the Link tag below).

Also, we should not clear BTRFS_ROOT_DEAD_RELOC_TREE from the root unless the root points to the reloc root we have.

Fix this by using clear_reloc_root(), which issues the memory barrier after setting the root's ->reloc_root to NULL and before clearing the bit BTRFS_ROOT_DEAD_RELOC_TREE from the root.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before 29531470b1bf1e8bd2df4941fe913106edbca615Affected 1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before 415f8665a969d3c906e4fd7c90fcbb4b357886f6Affected 1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before ee695a968aa73b1e67ccbf2133dc0e54381d32b2Affected 1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before 0bc25f0a2d1b3e0a691431c4d7aef36afcd527c5Affected 1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before ab48583aa9948205ff9a6470e23dbff74c565e24Affected 1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before 63d6b1f04cd91c825329712aa526215ffa5d11caAffected 1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before b78fe9563e2d5ae47805f1e5dc722c91fd30e1f8Affected ee08663380ffd5a45a1c87580fbc305e8413c235Affected 33823378ff2b510fd7b566f25bb18438aeb9b23bAffected 5.4.54 to before 5.5Affected 5.7.11 to before 5.8Affected
LinuxLinux	5.8Affected before 5.8Not affected 5.10.271 through 5.10.Not affected 5.15.222 through 5.15.Not affected 6.1.189 through 6.1.Not affected 6.6.158 through 6.6.Not affected 6.12.111 through 6.12.Not affected 6.18.53 through 6.18.Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before 29531470b1bf1e8bd2df4941fe913106edbca615Affected
1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before 415f8665a969d3c906e4fd7c90fcbb4b357886f6Affected
1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before ee695a968aa73b1e67ccbf2133dc0e54381d32b2Affected
1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before 0bc25f0a2d1b3e0a691431c4d7aef36afcd527c5Affected
1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before ab48583aa9948205ff9a6470e23dbff74c565e24Affected
1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before 63d6b1f04cd91c825329712aa526215ffa5d11caAffected
1dae7e0e58b484eaa43d530f211098fdeeb0f404 to before b78fe9563e2d5ae47805f1e5dc722c91fd30e1f8Affected
ee08663380ffd5a45a1c87580fbc305e8413c235Affected
33823378ff2b510fd7b566f25bb18438aeb9b23bAffected
5.4.54 to before 5.5Affected
5.7.11 to before 5.8Affected

LinuxLinux

5.8Affected
before 5.8Not affected
5.10.271 through 5.10.*Not affected
5.15.222 through 5.15.*Not affected
6.1.189 through 6.1.*Not affected
6.6.158 through 6.6.*Not affected
6.12.111 through 6.12.*Not affected
6.18.53 through 6.18.*Not affected
7.2 and laterNot affected

References

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