2013-04-17 19:19:55

by Kees Cook

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

From: Emese Revfy <[email protected]>

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 <[email protected]>
Reviewed-by: PaX Team <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Cc: [email protected]
---
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

2013-04-20 22:13:47

by Serge E. Hallyn

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

Quoting Kees Cook ([email protected]):
> From: Emese Revfy <[email protected]>
>
> 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 <[email protected]>

Sorry, not sure if this is applied yet,

Acked-by: Serge Hallyn <[email protected]>

> Reviewed-by: PaX Team <[email protected]>
> Signed-off-by: Kees Cook <[email protected]>
> Cc: [email protected]
> ---
> 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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2013-04-20 22:30:16

by Eric W. Biederman

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

"Serge E. Hallyn" <[email protected]> writes:

>
> Sorry, not sure if this is applied yet,
>
> Acked-by: Serge Hallyn <[email protected]>

I am pretty certain I saw Andrew apply this one and I have already seen
the stable back from gregkh go past.

Eric