diff options
authorJack Steiner <steiner@sgi.com>2009-04-02 16:59:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-02 19:05:11 -0700
commit4f032ac4122a77dbabf7a24b2739b2790448180f (patch)
parent2d09cde985702503970d7cc18d762fae17e1cf88 (diff)
cpumask: fix slab corruption caused by alloc_cpumask_var_node()
Fix slab corruption caused by alloc_cpumask_var_node() overwriting the tail end of an off-stack cpumask. The function zeros out cpumask bits beyond the last possible cpu. The starting point for zeroing should be the beginning of the mask offset by a byte count derived from the number of possible cpus. The offset was calculated in bits instead of bytes. This resulted in overwriting the end of the cpumask. Signed-off-by: Jack Steiner <steiner@sgi.com> Acked-by: Mike Travis <travis.sgi.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: <stable@kernel.org> [2.6.29.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 2 insertions, 2 deletions
diff --git a/lib/cpumask.c b/lib/cpumask.c
index 3389e2440da0..1f71b97de0f9 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -109,10 +109,10 @@ bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
/* FIXME: Bandaid to save us from old primitives which go to NR_CPUS. */
if (*mask) {
+ unsigned char *ptr = (unsigned char *)cpumask_bits(*mask);
unsigned int tail;
tail = BITS_TO_LONGS(NR_CPUS - nr_cpumask_bits) * sizeof(long);
- memset(cpumask_bits(*mask) + cpumask_size() - tail,
- 0, tail);
+ memset(ptr + cpumask_size() - tail, 0, tail);
return *mask != NULL;

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