[PATCH] signal: stop info leak via the tkill and the tgkill syscalls

[Kees Cook]

From: Emese Revfy <re.emese@xxxxxxxxx>

This fixes a kernel memory contents leak via the tkill and tgkill syscalls
for compat processes.

This is visible in the siginfo_t->_sifields._rt.si_sigval.sival_ptr field
when handling signals delivered from tkill.

The place of the infoleak:

int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
{
        ...
        put_user_ex(ptr_to_compat(from->si_ptr), &to->si_ptr);
        ...
}

Signed-off-by: Emese Revfy <re.emese@xxxxxxxxx>
Reviewed-by: PaX Team <pageexec@xxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 kernel/signal.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index dd72567..598dc06 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2948,7 +2948,7 @@ do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
 
 static int do_tkill(pid_t tgid, pid_t pid, int sig)
 {
-	struct siginfo info;
+	struct siginfo info = {};
 
 	info.si_signo = sig;
 	info.si_errno = 0;
-- 
1.7.9.5

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