posix-timers: Fix stack info leak in timer_create()
commit 6891c4509c792209c44ced55a60f13954cb50ef4 upstream.
If userland creates a timer without specifying a sigevent info, we'll
create one ourself, using a stack local variable. Particularly will we
use the timer ID as sival_int. But as sigev_value is a union containing
a pointer and an int, that assignment will only partially initialize
sigev_value on systems where the size of a pointer is bigger than the
size of an int. On such systems we'll copy the uninitialized stack bytes
from the timer_create() call to userland when the timer actually fires
and we're going to deliver the signal.
Initialize sigev_value with 0 to plug the stack info leak.
Found in the PaX patch, written by the PaX Team.
Fixes: 5a9fa7307285 ("posix-timers: kill ->it_sigev_signo and...")
Signed-off-by: Mathias Krause <firstname.lastname@example.org>
Cc: Oleg Nesterov <email@example.com>
Cc: Brad Spengler <firstname.lastname@example.org>
Cc: PaX Team <email@example.com>
Signed-off-by: Thomas Gleixner <firstname.lastname@example.org>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <email@example.com>
(cherry picked from commit 3cd3a349aa3519b88d29845c0bc36bcbae158e93)
Signed-off-by: Willy Tarreau <firstname.lastname@example.org>
Signed-off-by: Stefan Bader <email@example.com>
1 file changed