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

From: Ben Hutchings
Date: Mon Apr 22 2013 - 10:43:00 EST


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

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

From: Emese Revfy <re.emese@xxxxxxxxx>

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@xxxxxxxxx>
Reviewed-by: PaX Team <pageexec@xxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
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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