Patch "mm/mempolicy.c: fix error handling in set_mempolicy and mbind." has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    mm/mempolicy.c: fix error handling in set_mempolicy and mbind.

to the 4.9-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:
     mm-mempolicy.c-fix-error-handling-in-set_mempolicy-and-mbind.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From cf01fb9985e8deb25ccf0ea54d916b8871ae0e62 Mon Sep 17 00:00:00 2001
From: Chris Salls <salls@cs.ucsb.edu>
Date: Fri, 7 Apr 2017 23:48:11 -0700
Subject: mm/mempolicy.c: fix error handling in set_mempolicy and mbind.

From: Chris Salls <salls@cs.ucsb.edu>

commit cf01fb9985e8deb25ccf0ea54d916b8871ae0e62 upstream.

In the case that compat_get_bitmap fails we do not want to copy the
bitmap to the user as it will contain uninitialized stack data and leak
sensitive data.

Signed-off-by: Chris Salls <salls@cs.ucsb.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 mm/mempolicy.c |   20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1524,7 +1524,6 @@ COMPAT_SYSCALL_DEFINE5(get_mempolicy, in
 COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
 		       compat_ulong_t, maxnode)
 {
-	long err = 0;
 	unsigned long __user *nm = NULL;
 	unsigned long nr_bits, alloc_size;
 	DECLARE_BITMAP(bm, MAX_NUMNODES);
@@ -1533,14 +1532,13 @@ COMPAT_SYSCALL_DEFINE3(set_mempolicy, in
 	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
 
 	if (nmask) {
-		err = compat_get_bitmap(bm, nmask, nr_bits);
+		if (compat_get_bitmap(bm, nmask, nr_bits))
+			return -EFAULT;
 		nm = compat_alloc_user_space(alloc_size);
-		err |= copy_to_user(nm, bm, alloc_size);
+		if (copy_to_user(nm, bm, alloc_size))
+			return -EFAULT;
 	}
 
-	if (err)
-		return -EFAULT;
-
 	return sys_set_mempolicy(mode, nm, nr_bits+1);
 }
 
@@ -1548,7 +1546,6 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulo
 		       compat_ulong_t, mode, compat_ulong_t __user *, nmask,
 		       compat_ulong_t, maxnode, compat_ulong_t, flags)
 {
-	long err = 0;
 	unsigned long __user *nm = NULL;
 	unsigned long nr_bits, alloc_size;
 	nodemask_t bm;
@@ -1557,14 +1554,13 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulo
 	alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
 
 	if (nmask) {
-		err = compat_get_bitmap(nodes_addr(bm), nmask, nr_bits);
+		if (compat_get_bitmap(nodes_addr(bm), nmask, nr_bits))
+			return -EFAULT;
 		nm = compat_alloc_user_space(alloc_size);
-		err |= copy_to_user(nm, nodes_addr(bm), alloc_size);
+		if (copy_to_user(nm, nodes_addr(bm), alloc_size))
+			return -EFAULT;
 	}
 
-	if (err)
-		return -EFAULT;
-
 	return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
 }
 


Patches currently in stable-queue which might be from salls@cs.ucsb.edu are

queue-4.9/mm-mempolicy.c-fix-error-handling-in-set_mempolicy-and-mbind.patch