diff options
authorMathias Krause <minipli@googlemail.com>2014-10-04 23:06:39 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-14 09:00:10 -0800
commiteeae838b835b6ffb7ac7f6bcbc800488a61f873b (patch)
parent589bacbccdb444ca31aebb1128fd8fc0a436151b (diff)
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 <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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 1 insertions, 0 deletions
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;