diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-09-20 09:41:00 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-09-20 09:41:00 -0700 |
| commit | 0a15ba6b0c3adec5842d4252c3e5d2ca935e9948 (patch) | |
| tree | 2c9c55b35d6544250b389bed5dfbfe96a12e6717 /fs | |
| parent | fecbe78ac0e7bb5cdae232444e649a3103d9a917 (diff) | |
| parent | c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd (diff) | |
Merge tag 'timers-urgent-2026-09-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer race fixes from Ingo Molnar:
- Fix timer signal <-> exec() race, to prevent UAF (Thomas Gleixner)
- Clean up POSIX CPU timers right after de_thread(), to prevent UAF
(Hyunwoo Kim)
- Fix POSIX CPU timers race between expiry and timer_settime(),
to prevent UAF (Thomas Gleixner)
* tag 'timers-urgent-2026-09-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list
exec: Cleanup POSIX timers right after de_thread()
signal: Prevent exec() race
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/exec.c | 29 |
1 files changed, 21 insertions, 8 deletions
diff --git a/fs/exec.c b/fs/exec.c index d3081c8f7c10..819643408e6d 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1115,6 +1115,17 @@ static struct file *bprm_identity_file(const struct linux_binprm *bprm) return bprm->file; } +static void posixtimer_exec(struct task_struct *me) +{ +#ifdef CONFIG_POSIX_TIMERS + spin_lock_irq(&me->sighand->siglock); + posix_cpu_timers_exit(me); + spin_unlock_irq(&me->sighand->siglock); + exit_itimers(me); + flush_itimer_signals(); +#endif +} + /* * Calling this is the point of no return. None of the failures will be * seen by userspace since either the process is already taking a fatal @@ -1152,6 +1163,16 @@ int begin_new_exec(struct linux_binprm * bprm) retval = de_thread(me); if (retval) goto out; + + /* + * This must be done here to ensure that POSIX CPU timers which were + * armed on the current task are dequeued from me::posix_cputimers. + * Otherwise in case of a TID switch the deletion of the related POSIX + * timer would not remove an enqueued timer because the TID lookup + * of the old TID fails. + */ + posixtimer_exec(me); + /* see the comment in check_unsafe_exec() */ current->fs->in_exec = 0; /* @@ -1206,14 +1227,6 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) goto out_unlock; -#ifdef CONFIG_POSIX_TIMERS - spin_lock_irq(&me->sighand->siglock); - posix_cpu_timers_exit(me); - spin_unlock_irq(&me->sighand->siglock); - exit_itimers(me); - flush_itimer_signals(); -#endif - /* * Make the signal table private. */ |