Patch "__bitmap_parselist: fix bug in empty string handling" has been added to the 3.14-stable tree

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

__bitmap_parselist: fix bug in empty string handling

to the 3.14-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:
__bitmap_parselist-fix-bug-in-empty-string-handling.patch
and it can be found in the queue-3.14 subdirectory.

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

From: Chris Metcalf <[email protected]>
Date: Thu, 25 Jun 2015 15:02:08 -0700
Subject: __bitmap_parselist: fix bug in empty string handling

From: Chris Metcalf <[email protected]>

commit 2528a8b8f457d7432552d0e2b6f0f4046bb702f4 upstream.

bitmap_parselist("", &mask, nmaskbits) will erroneously set bit zero in the mask. The same bug is visible in cpumask_parselist() since it is layered on top of the bitmask code, e.g. if you boot with "isolcpus=", you will actually end up with cpu zero isolated.

The bug was introduced in commit 4b060420a596 ("bitmap, irq: add smp_affinity_list interface to /proc/irq") when bitmap_parselist() was generalized to support userspace as well as kernelspace.

---
 lib/bitmap.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

@@ -603,12 +603,12 @@ static int __bitmap_parselist(const char
 	unsigned a, b;
 	int c, old_c, totaldigits;
 	const char __user __force *ubuf = (const char __user __force *)buf;
-	int exp_digit, in_range;
+	int at_start, in_range;
 
 	totaldigits = c = 0;
 	bitmap_zero(maskp, nmaskbits);
 	do {
-		exp_digit = 1;
+		at_start = 1;
 		in_range = 0;
 		a = b = 0;
 

@@ -637,11 +637,10 @@ static int __bitmap_parselist(const char
 				break;
 
 			if (c == '-') {
-				if (exp_digit || in_range)
+				if (at_start || in_range)
 					return -EINVAL;
 				b = 0;
 				in_range = 1;
-				exp_digit = 1;
 				continue;
 			}
 

@@ -651,16 +650,18 @@ static int __bitmap_parselist(const char
 			b = b * 10 + (c - '0');
 			if (!in_range)
 				a = b;
-			exp_digit = 0;
+			at_start = 0;
 			totaldigits++;
 		}
 		if (!(a <= b))
 			return -EINVAL;
 		if (b >= nmaskbits)
 			return -ERANGE;
-		while (a <= b) {
-			set_bit(a, maskp);
-			a++;
+		if (!at_start) {
+			while (a <= b) {
+				set_bit(a, maskp);
+				a++;
+			}
 		}
 	} while (buflen && c == ',');
 	return 0;

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

queue-3.14/__bitmap_parselist-fix-bug-in-empty-string-handling.patch