CVE-2026-53048 gfs2: prevent NULL pointer dereference during unmount

In the Linux kernel, the following vulnerability has been resolved: gfs2: prevent NULL pointer dereference during unmount When flushing out outstanding glock work during an unmount, gfs2logflush can be called when sdp-sdjdesc has already been deallocated and sdp-sdjdesc is NULL. Commit 35264909e9...