From: Thadeu Lima de Souza Cascardo cascardo@canonical.com
mainline inclusion from mainline-v6.0-rc1 commit e362359ace6f87c201531872486ff295df306d13 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5MGOO CVE: CVE-2022-2585
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Commit 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") started looking up tasks by PID when deleting a CPU timer.
When a non-leader thread calls execve, it will switch PIDs with the leader process. Then, as it calls exit_itimers, posix_cpu_timer_del cannot find the task because the timer still points out to the old PID.
That means that armed timers won't be disarmed, that is, they won't be removed from the timerqueue_list. exit_itimers will still release their memory, and when that list is later processed, it leads to a use-after-free.
Clean up the timers from the de-threaded task before freeing them. This prevents a reported use-after-free.
Fixes: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@canonical.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20220809170751.164716-1-cascardo@canonical.com
Conflicts: fs/exec.c
Signed-off-by: Yu Liao liaoyu15@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- fs/exec.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/exec.c b/fs/exec.c index cf2077bffc0a..fd7c0320a9bf 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1278,6 +1278,9 @@ int begin_new_exec(struct linux_binprm * bprm) bprm->mm = NULL;
#ifdef CONFIG_POSIX_TIMERS + spin_lock_irq(&me->sighand->siglock); + posix_cpu_timers_exit(me); + spin_unlock_irq(&me->sighand->siglock); exit_itimers(me->signal); flush_itimer_signals(); #endif