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Commit 2528a8b8 authored by Chris Metcalf's avatar Chris Metcalf Committed by Linus Torvalds
Browse files

__bitmap_parselist: fix bug in empty string handling 



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 4b060420 ("bitmap, irq: add
smp_affinity_list interface to /proc/irq") when bitmap_parselist() was
generalized to support userspace as well as kernelspace.

Fixes: 4b060420 ("bitmap, irq: add smp_affinity_list interface to /proc/irq")
Signed-off-by: default avatarChris Metcalf <cmetcalf@ezchip.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4f973c63

lib/bitmap.c

+9 −8
Original line number Diff line number Diff line
@@ -506,12 +506,12 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, 
	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;
@@ -540,11 +540,10 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, 
				break;



			if (c == '-') {

				if (exp_digit || in_range)

				if (at_start || in_range)

					return -EINVAL;

				b = 0;

				in_range = 1;

				exp_digit = 1;

				continue;

			}
@@ -554,17 +553,19 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, 
			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;

		if (!at_start) {

			while (a <= b) {

				set_bit(a, maskp);

				a++;

			}

		}

	} while (buflen && c == ',');

	return 0;

}