From: Mathias Krause Date: Sat, 4 Oct 2014 21:06:39 +0000 (+0200) Subject: posix-timers: Fix stack info leak in timer_create() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f9b6264a0fdf9268e61a065177dde1c8f823dfc0;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git 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 Cc: Oleg Nesterov Cc: Brad Spengler Cc: PaX Team Link: http://lkml.kernel.org/r/1412456799-32339-1-git-send-email-minipli@googlemail.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 424c2d4265c9..77e6b83c0431 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -634,6 +634,7 @@ 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;