waitid(): Add missing access_ok() checks

commit 96ca579a1ecc943b75beba58bebb0356f6cc4b51 upstream.

Adds missing access_ok() checks.

CVE-2017-5123

Reported-by: Chris Salls <chrissalls5@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 4c48abe91be0 ("waitid(): switch copyout of siginfo to unsafe_put_user()")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/exit.c b/kernel/exit.c
index 6d31fc5ba50d77bfd15357aa2b1f9578d48d9c9a..135b36985f8a2d9ca30a1a33737cb5cc1e3f0bc3 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1611,6 +1611,9 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
        if (!infop)
                return err;
 
+       if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop)))
+               goto Efault;
+
        user_access_begin();
        unsafe_put_user(signo, &infop->si_signo, Efault);
        unsafe_put_user(0, &infop->si_errno, Efault);
@@ -1736,6 +1739,9 @@ COMPAT_SYSCALL_DEFINE5(waitid,
        if (!infop)
                return err;
 
+       if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop)))
+               goto Efault;
+
        user_access_begin();
        unsafe_put_user(signo, &infop->si_signo, Efault);
        unsafe_put_user(0, &infop->si_errno, Efault);