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

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Message-Id: <1366226365-15594-1-git-send-email-keescook@chromium.org>
Date:	Wed, 17 Apr 2013 12:19:25 -0700
From:	Kees Cook <keescook@...omium.org>
To:	linux-kernel@...r.kernel.org
Cc:	Al Viro <viro@...iv.linux.org.uk>, Oleg Nesterov <oleg@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	PaX Team <pageexec@...email.hu>,
	Kees Cook <keescook@...omium.org>,
	Emese Revfy <re.emese@...il.com>, stable@...r.kernel.org
Subject: [PATCH] signal: stop info leak via the tkill and the tgkill syscalls

From: Emese Revfy <re.emese@...il.com>

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@...il.com>
Reviewed-by: PaX Team <pageexec@...email.hu>
Signed-off-by: Kees Cook <keescook@...omium.org>
Cc: stable@...r.kernel.org
---
 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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