CVE-2026-63804

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.
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

History

29 Jul 2026, 20:02

Type Values Removed Values Added
CPE cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 7.8
First Time Linux linux Kernel
Linux
CWE CWE-416
References () https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093 - () https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093 - Patch
References () https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757 - () https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757 - Patch
References () https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0 - () https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0 - Patch
References () https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0 - () https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0 - Patch
References () https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081 - () https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081 - Patch

19 Jul 2026, 12:16

Type Values Removed Values Added
New CVE

Information

Published : 2026-07-19 12:16

Updated : 2026-07-29 20:02


NVD link : CVE-2026-63804

Mitre link : CVE-2026-63804

CVE.ORG link : CVE-2026-63804


JSON object : View

Products Affected

linux

  • linux_kernel
CWE
CWE-416

Use After Free