From 4f032ac4122a77dbabf7a24b2739b2790448180f Mon Sep 17 00:00:00 2001 From: Jack Steiner Date: Thu, 2 Apr 2009 16:59:48 -0700 Subject: [PATCH] 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 Acked-by: Mike Travis Acked-by: Ingo Molnar Cc: Rusty Russell Cc: Stephen Rothwell Cc: [2.6.29.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/cpumask.c | 4 ++-- 1 file 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) #endif /* 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; -- 2.30.2