waitid(): Add missing access_ok() checks
authorKees Cook <keescook@chromium.org>
Mon, 9 Oct 2017 18:36:52 +0000 (11:36 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 10 Oct 2017 00:03:31 +0000 (17:03 -0700)
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()")
Cc: stable@kernel.org # 4.13
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/exit.c

index f2cd53e..cf28528 100644 (file)
@@ -1610,6 +1610,9 @@ 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);
@@ -1735,6 +1738,9 @@ 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);