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__bitmap_parselist: fix bug in empty string handling 

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 4b060420a5 ("bitmap, irq: add
smp_affinity_list interface to /proc/irq") when bitmap_parselist() was
generalized to support userspace as well as kernelspace.

Fixes: 4b060420a5 ("bitmap, irq: add smp_affinity_list interface to /proc/irq")
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chris Metcalf 2015-06-25 15:02:08 -07:00 committed by Greg Kroah-Hartman
parent 21dd5b3d73
commit bf95f46c3f
1 changed files with 9 additions and 8 deletions
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17
lib/bitmap.c
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@ -603,12 +603,12 @@ 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;
@ -637,11 +637,10 @@ 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;
}
@ -651,16 +650,18 @@ 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;
while (a <= b) {
set_bit(a, maskp);
a++;
if (!at_start) {
while (a <= b) {
set_bit(a, maskp);
a++;
}
}
} while (buflen && c == ',');
return 0;