svn commit: r317936 - stable/11/sys/compat/linux

[Dmitry Chagin]

Author: dchagin
Date: Mon May  8 10:51:30 2017
New Revision: 317936
URL: https://svnweb.freebsd.org/changeset/base/317936

Log:
  MFC r317645:
  
  Fix NULL pointer dereference in futex_wake_op() in case when the same
  address specified for arguments uaddr and uaddr2.
  
  PR:		218987

Modified:
  stable/11/sys/compat/linux/linux_futex.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/compat/linux/linux_futex.c
==============================================================================
--- stable/11/sys/compat/linux/linux_futex.c	Mon May  8 09:14:41 2017	(r317935)
+++ stable/11/sys/compat/linux/linux_futex.c	Mon May  8 10:51:30 2017	(r317936)
@@ -952,6 +952,11 @@ retry1:
 		    args->uaddr, args->val, args->uaddr2, args->val3,
 		    args->timeout);
 
+		if (args->uaddr == args->uaddr2) {
+			LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
+			return (EINVAL);
+		}
+
 retry2:
 		error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK);
 		if (error) {
@@ -959,9 +964,7 @@ retry2:
 			return (error);
 		}
 
-		if (args->uaddr != args->uaddr2)
-			error = futex_get(args->uaddr2, NULL, &f2,
-			    flags | FUTEX_DONTLOCK);
+		error = futex_get(args->uaddr2, NULL, &f2, flags | FUTEX_DONTLOCK);
 		if (error) {
 			futex_put(f, NULL);