-stable review patch. If anyone has any objections, please let us know.
---------------------
From: Jack Steiner <[email protected]>
upstream commit: 4f032ac4122a77dbabf7a24b2739b2790448180f
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 <[email protected]>
Acked-by: Mike Travis <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Chris Wright <[email protected]>
---
lib/cpumask.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -109,10 +109,10 @@ bool alloc_cpumask_var_node(cpumask_var_
#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;