CVE-2026-63804

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> gfs2: fix use-after-free in gfs2_qd_dealloc<br /> <br /> gfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(),<br /> accesses the superblock object sdp through qd-&gt;qd_sbd after freeing qd.<br /> It does so to decrement sd_quota_count and wake up sd_kill_wait.<br /> <br /> However, by the time the RCU callback runs, gfs2_put_super() may have<br /> already freed sdp via free_sbd(). This can happen when<br /> gfs2_quota_cleanup() is called during unmount: it disposes of quota<br /> objects via call_rcu() and then waits on sd_kill_wait with a 60-second<br /> timeout. If the timeout expires, or if gfs2_gl_hash_clear() triggers<br /> additional qd_put() calls that schedule more RCU callbacks after the<br /> wait completes, gfs2_put_super() will proceed to free the superblock<br /> while RCU callbacks referencing it are still pending.<br /> <br /> Add an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure<br /> all pending RCU callbacks (including gfs2_qd_dealloc) have completed<br /> before the superblock is freed.