{"id":"CVE-2026-63804","state":"PUBLISHED","title":"gfs2: fix use-after-free in gfs2_qd_dealloc","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: fix use-after-free in gfs2_qd_dealloc\n\ngfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(),\naccesses the superblock object sdp through qd->qd_sbd after freeing qd.\nIt does so to decrement sd_quota_count and wake up sd_kill_wait.\n\nHowever, by the time the RCU callback runs, gfs2_put_super() may have\nalready freed sdp via free_sbd().  This can happen when\ngfs2_quota_cleanup() is called during unmount: it disposes of quota\nobjects via call_rcu() and then waits on sd_kill_wait with a 60-second\ntimeout.  If the timeout expires, or if gfs2_gl_hash_clear() triggers\nadditional qd_put() calls that schedule more RCU callbacks after the\nwait completes, gfs2_put_super() will proceed to free the superblock\nwhile RCU callbacks referencing it are still pending.\n\nAdd an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure\nall pending RCU callbacks (including gfs2_qd_dealloc) have completed\nbefore the superblock is freed.","publishedAt":"2026-07-19T12:02:09.111Z","updatedAt":"2026-08-17T04:51:09.991Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"4fe388218826df8607ae41a6305df67db08a9093","versionType":"git"},{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"8745d9f7e1682c39f0a1578895ac74205e2a6757","versionType":"git"},{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0","versionType":"git"},{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0","versionType":"git"},{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"f9c9ec2c319f843b70ecdf939d48b52d189bc081","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/gfs2/super.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.6","versionType":"semver"},{"version":"6.6.144","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/gfs2/super.c"]}],"references":["https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093","https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757","https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0","https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0","https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63804.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63804","state":"PUBLISHED","datePublished":"2026-07-19T12:02:09.111Z","dateUpdated":"2026-08-17T04:51:09.991Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.013Z"},"containers":{"cna":{"title":"gfs2: fix use-after-free in gfs2_qd_dealloc","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: fix use-after-free in gfs2_qd_dealloc\n\ngfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(),\naccesses the superblock object sdp through qd->qd_sbd after freeing qd.\nIt does so to decrement sd_quota_count and wake up sd_kill_wait.\n\nHowever, by the time the RCU callback runs, gfs2_put_super() may have\nalready freed sdp via free_sbd().  This can happen when\ngfs2_quota_cleanup() is called during unmount: it disposes of quota\nobjects via call_rcu() and then waits on sd_kill_wait with a 60-second\ntimeout.  If the timeout expires, or if gfs2_gl_hash_clear() triggers\nadditional qd_put() calls that schedule more RCU callbacks after the\nwait completes, gfs2_put_super() will proceed to free the superblock\nwhile RCU callbacks referencing it are still pending.\n\nAdd an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure\nall pending RCU callbacks (including gfs2_qd_dealloc) have completed\nbefore the superblock is freed."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"4fe388218826df8607ae41a6305df67db08a9093","versionType":"git"},{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"8745d9f7e1682c39f0a1578895ac74205e2a6757","versionType":"git"},{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0","versionType":"git"},{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0","versionType":"git"},{"version":"a475c5dd16e57c570113eccba51955b5df8bb052","status":"affected","lessThan":"f9c9ec2c319f843b70ecdf939d48b52d189bc081","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/gfs2/super.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.6","versionType":"semver"},{"version":"6.6.144","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/gfs2/super.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093"},{"url":"https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757"},{"url":"https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0"},{"url":"https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0"},{"url":"https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:51:09.991Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.6.144"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.12.95"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.18.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"7.1.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}