6.17-stable review patch. If anyone has any objections, please let me know.
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From: Eslam Khafagy eslam.medhat1993@gmail.com
[ Upstream commit e0fd4d42e27f761e9cc82801b3f183e658dc749d ]
When posix timer creation is set to allocate a given timer ID and the access to the user space value faults, the function terminates without freeing the already allocated posix timer structure.
Move the allocation after the user space access to cure that.
[ tglx: Massaged change log ]
Fixes: ec2d0c04624b3 ("posix-timers: Provide a mechanism to allocate a given timer ID") Reported-by: syzbot+9c47ad18f978d4394986@syzkaller.appspotmail.com Suggested-by: Cyrill Gorcunov gorcunov@gmail.com Signed-off-by: Eslam Khafagy eslam.medhat1993@gmail.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Frederic Weisbecker frederic@kernel.org Link: https://patch.msgid.link/20251114122739.994326-1-eslam.medhat1993@gmail.com Closes: https://lore.kernel.org/all/69155df4.a70a0220.3124cb.0017.GAE@google.com/T/ Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/time/posix-timers.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index 8b582174b1f94..42db8396f1999 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -476,12 +476,6 @@ static int do_timer_create(clockid_t which_clock, struct sigevent *event, if (!kc->timer_create) return -EOPNOTSUPP;
- new_timer = alloc_posix_timer(); - if (unlikely(!new_timer)) - return -EAGAIN; - - spin_lock_init(&new_timer->it_lock); - /* Special case for CRIU to restore timers with a given timer ID. */ if (unlikely(current->signal->timer_create_restore_ids)) { if (copy_from_user(&req_id, created_timer_id, sizeof(req_id))) @@ -491,6 +485,12 @@ static int do_timer_create(clockid_t which_clock, struct sigevent *event, return -EINVAL; }
+ new_timer = alloc_posix_timer(); + if (unlikely(!new_timer)) + return -EAGAIN; + + spin_lock_init(&new_timer->it_lock); + /* * Add the timer to the hash table. The timer is not yet valid * after insertion, but has a unique ID allocated.