Threats Tagged 'cve-2026-63804'

These are all security issues fixed in the kernel-devel-7.1.4-1.1 package on the GA media of openSUSE Tumbleweed.

A use-after-free vulnerability exists in the Linux kernel's GFS2 filesystem code in the gfs2_qd_dealloc function. The issue arises because the function accesses a superblock object after it may have been freed, leading to potential memory corruption. The vulnerability is related to the handling of RCU callbacks during unmount operations. This flaw has been resolved by adding an rcu_barrier() call to ensure all RCU callbacks complete before freeing the superblock.

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.