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.
References
Configurations
Configuration 1 (hide)
|
History
29 Jul 2026, 20:02
| Type | Values Removed | Values Added |
|---|---|---|
| CPE | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.8 |
| First Time |
Linux linux Kernel
Linux |
|
| CWE | CWE-416 | |
| References | () https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093 - Patch | |
| References | () https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757 - Patch | |
| References | () https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0 - Patch | |
| References | () https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0 - Patch | |
| References | () 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
