CVE-2026-63804gfs2: fix use-after-free in gfs2_qd_dealloc
Updated under an hour ago ()
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In the Linux kernel, the following vulnerability has been resolved: gfs2: fix use-after-free in gfs2_qd_dealloc gfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(), accesses the superblock object sdp through qd->qd_sbd after freeing qd. It does so to decrement sd_quota_count and wake up sd_kill_wait. However, by the time the RCU callback runs, gfs2_put_super() may have already freed sdp via free_sbd(). This can happen when gfs2_quota_cleanup() is called during unmount: it disposes of quota objects via call_rcu() and then waits on sd_kill_wait with a 60-second timeout. If the timeout expires, or if gfs2_gl_hash_clear() triggers additional qd_put() calls that schedule more RCU callbacks after the wait completes, gfs2_put_super() will proceed to free the superblock while RCU callbacks referencing it are still pending. Add an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure all pending RCU callbacks (including gfs2_qd_dealloc) have completed before the superblock is freed.
- CVSS
- 7.8 HIGH (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Analyzed
- Record last updated
- Aug 17, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from a475c5dd16e57c570113eccba51955b5df8bb052 before 4fe388218826df8607ae41a6305df67db08a9093; from a475c5dd16e57c570113eccba51955b5df8bb052 before 8745d9f7e1682c39f0a1578895ac74205e2a6757; from a475c5dd16e57c570113eccba51955b5df8bb052 before b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0; from a475c5dd16e57c570113eccba51955b5df8bb052 before 9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0; from a475c5dd16e57c570113eccba51955b5df8bb052 before f9c9ec2c319f843b70ecdf939d48b52d189bc081 | CNA record |
linux linux_kernel linux:linux_kernel | from 6.6 before 6.6.144; from 6.7 before 6.12.95; from 6.13 before 6.18.38; from 6.19 before 7.1.3 | NVD |
References
- https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093patch
- https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757patch
- https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0patch
- https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0patch
- https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.