linux-kernel - [51/75] kernel/signal.c: stop info leak via the tkill and the tgkill syscalls

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Message-ID: <lsq.1366640759.686764292@decadent.org.uk>
Date:	Mon, 22 Apr 2013 15:25:59 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Emese Revfy" <re.emese@...il.com>,
	"Serge Hallyn" <serge.hallyn@...onical.com>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	"PaX Team" <pageexec@...email.hu>,
	"Al Viro" <viro@...iv.linux.org.uk>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Kees Cook" <keescook@...omium.org>,
	"Oleg Nesterov" <oleg@...hat.com>
Subject: [51/75] kernel/signal.c: stop info leak via the tkill and the
 tgkill syscalls

3.2.44-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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

commit b9e146d8eb3b9ecae5086d373b50fa0c1f3e7f0f upstream.

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: Al Viro <viro@...iv.linux.org.uk>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Serge Hallyn <serge.hallyn@...onical.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 kernel/signal.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2790,7 +2790,7 @@ do_send_specific(pid_t tgid, pid_t pid,
 
 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;

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