userns: prevent speculative execution

[mirror_ubuntu-artful-kernel.git] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index c5548faa9f377c5bf01f4a4db8e3020448565469..135b36985f8a2d9ca30a1a33737cb5cc1e3f0bc3 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1601,18 +1601,19 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
        struct waitid_info info = {.status = 0};
        long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
        int signo = 0;
+
        if (err > 0) {
                signo = SIGCHLD;
                err = 0;
-       }
-
-       if (!err) {
                if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
                        return -EFAULT;
        }
        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);
@@ -1724,21 +1725,23 @@ COMPAT_SYSCALL_DEFINE5(waitid,
        if (err > 0) {
                signo = SIGCHLD;
                err = 0;
-       }
-
-       if (!err && uru) {
-               /* kernel_waitid() overwrites everything in ru */
-               if (COMPAT_USE_64BIT_TIME)
-                       err = copy_to_user(uru, &ru, sizeof(ru));
-               else
-                       err = put_compat_rusage(&ru, uru);
-               if (err)
-                       return -EFAULT;
+               if (uru) {
+                       /* kernel_waitid() overwrites everything in ru */
+                       if (COMPAT_USE_64BIT_TIME)
+                               err = copy_to_user(uru, &ru, sizeof(ru));
+                       else
+                               err = put_compat_rusage(&ru, uru);
+                       if (err)
+                               return -EFAULT;
+               }
        }
 
        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);