Messages in this thread Patch in this message | | | Date | Fri, 15 May 2015 10:06:16 +0200 | From | Willy Tarreau <> | Subject | [ 46/48] posix-timers: Fix stack info leak in timer_create() |
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2.6.32-longterm review patch. If anyone has any objections, please let me know.
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From: Mathias Krause <minipli@googlemail.com>
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 <minipli@googlemail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Brad Spengler <spender@grsecurity.net> Cc: PaX Team <pageexec@freemail.hu> Link: http://lkml.kernel.org/r/1412456799-32339-1-git-send-email-minipli@googlemail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> (cherry picked from commit 3cd3a349aa3519b88d29845c0bc36bcbae158e93)
Signed-off-by: Willy Tarreau <w@1wt.eu> --- kernel/posix-timers.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 5e76d22..f2335e8 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -578,6 +578,7 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock, goto out; } } else { + memset(&event.sigev_value, 0, sizeof(event.sigev_value)); event.sigev_notify = SIGEV_SIGNAL; event.sigev_signo = SIGALRM; event.sigev_value.sival_int = new_timer->it_id; -- 1.7.12.2.21.g234cd45.dirty
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