Patch "fix infoleak in waitid(2)" has been added to the 4.13-stable tree

This is a note to let you know that I've just added the patch titled

fix infoleak in waitid(2)

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
fix-infoleak-in-waitid-2.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Al Viro <[email protected]>
Date: Fri, 29 Sep 2017 13:43:15 -0400
Subject: fix infoleak in waitid(2)

From: Al Viro <[email protected]>

commit 6c85501f2fabcfc4fc6ed976543d252c4eaf4be9 upstream.

kernel_waitid() can return a PID, an error or 0. rusage is filled in the first case and waitid(2) rusage should've been copied out exactly in that case, *not* whenever kernel_waitid() has not returned an error. Compat variant shares that braino; none of kernel_wait4() callers do, so the below ought to fix it.

---
 kernel/exit.c |   23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

@@ -1601,12 +1601,10 @@ SYSCALL_DEFINE5(waitid, int, which, pid_
 	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;
 	}

@@ -1724,16 +1722,15 @@ 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)

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/fix-infoleak-in-waitid-2.patch queue-4.13/fs-proc-report-eip-esp-in-prod-pid-stat-for-coredumping.patch