Answer in brief
CVE-2026-63804 records a Unknown severity vulnerability in gfs2: fix use-after-free in gfs2_qd_dealloc. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=a475c5dd16e57c570113eccba51955b5df8bb052 <4fe388218826df8607ae41a6305df67db08a9093 || >=a475c5dd16e57c570113eccba51955b5df8bb052 <8745d9f7e1682c39f0a1578895ac74205e2a6757 || >=a475c5dd16e57c570113eccba51955b5df8bb052 <b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0 || >=a475c5dd16e57c570113eccba51955b5df8bb052 <9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0 || >=a475c5dd16e57c570113eccba51955b5df8bb052 <f9c9ec2c319f843b70ecdf939d48b52d189bc081 | 4fe388218826df8607ae41a6305df67db08a9093, 8745d9f7e1682c39f0a1578895ac74205e2a6757, b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0, 9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0, f9c9ec2c319f843b70ecdf939d48b52d189bc081 |
| Linux/Linuxgeneric | 6.6 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 17, 2026
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.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-63804 records a Unknown severity vulnerability in gfs2: fix use-after-free in gfs2_qd_dealloc. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=a475c5dd16e57c570113eccba51955b5df8bb052 <4fe388218826df8607ae41a6305df67db08a9093 || >=a475c5dd16e57c570113eccba51955b5df8bb052 <8745d9f7e1682c39f0a1578895ac74205e2a6757 || >=a475c5dd16e57c570113eccba51955b5df8bb052 <b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0 || >=a475c5dd16e57c570113eccba51955b5df8bb052 <9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0 || >=a475c5dd16e57c570113eccba51955b5df8bb052 <f9c9ec2c319f843b70ecdf939d48b52d189bc081 | 4fe388218826df8607ae41a6305df67db08a9093, 8745d9f7e1682c39f0a1578895ac74205e2a6757, b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0, 9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0, f9c9ec2c319f843b70ecdf939d48b52d189bc081 |
| Linux/Linuxgeneric | 6.6 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 17, 2026
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.
Quoted source text, attributed separately from HOL analysis.