{"id":"CVE-2026-63804","summary":"gfs2: fix use-after-free in gfs2_qd_dealloc","details":"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-\u003eqd_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.","modified":"2026-07-23T09:59:47.335513809Z","published":"2026-07-19T12:02:09.111Z","related":["openSUSE-SU-2026:11339-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63804.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63804.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63804"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"a475c5dd16e57c570113eccba51955b5df8bb052"},{"fixed":"4fe388218826df8607ae41a6305df67db08a9093"},{"fixed":"8745d9f7e1682c39f0a1578895ac74205e2a6757"},{"fixed":"b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0"},{"fixed":"9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0"},{"fixed":"f9c9ec2c319f843b70ecdf939d48b52d189bc081"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63804.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.6.0"},{"fixed":"6.6.144"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.95"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.38"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.3"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63804.json"}}],"schema_version":"1.7.5"}