ALSA timer instance object has a couple of linked lists and they are unlinked unconditionally at snd_timer_stop(). Meanwhile snd_timer_interrupt() unlinks it, but it calls list_del() which leaves the element list itself unchanged. This ends up with unlinking twice, and it was caught by syzkaller fuzzer. Upstream patch: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ee8413b01045c74340aa13ad5bdf905de32be736 CVE-ID request and assignment: http://seclists.org/oss-sec/2016/q1/133 http://seclists.org/oss-sec/2016/q1/410
This was fixed with 4.3.5 with: commit baa3a675b24fe17d5e514d71561d97f46bc6086f Author: Takashi Iwai <tiwai> Date: Wed Jan 13 21:35:06 2016 +0100 ALSA: timer: Fix double unlink of active_list commit ee8413b01045c74340aa13ad5bdf905de32be736 upstream. and in 4.4.1 with: commit 3c0e535fee2e67d06220e676cbf7b69099d741ce Author: Takashi Iwai <tiwai> Date: Wed Jan 13 21:35:06 2016 +0100 ALSA: timer: Fix double unlink of active_list commit ee8413b01045c74340aa13ad5bdf905de32be736 upstream. All Fedora branches are on those or newer. This issue is solved in Fedora.
Statement: This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 6, 7 and MRG-2. This has been rated as having Low security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.