From: Prasanna Meda <pmeda@akamai.com>
- Race in mempool_resize: memcpy can copy at the end of the kmalloced
elements.
- When new_min_nr is same as min_nr, instead of reallocate and copy, just
return, changed '<' to '<='.
- Changed while condition to the same sense of if condition from '>' to
'<'; it is easy to think with only one of the left and right brains at a
time.
Signed-off-by: Prasanna Meda <pmeda@akamai.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/mm/mempool.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff -puN mm/mempool.c~mempool-protect-buffer-overflow-in-mempool_resize mm/mempool.c
--- 25/mm/mempool.c~mempool-protect-buffer-overflow-in-mempool_resize Thu Feb 17 16:57:45 2005
+++ 25-akpm/mm/mempool.c Thu Feb 17 16:57:45 2005
@@ -114,8 +114,8 @@ int mempool_resize(mempool_t *pool, int
BUG_ON(new_min_nr <= 0);
spin_lock_irqsave(&pool->lock, flags);
- if (new_min_nr < pool->min_nr) {
- while (pool->curr_nr > new_min_nr) {
+ if (new_min_nr <= pool->min_nr) {
+ while (new_min_nr < pool->curr_nr) {
element = remove_element(pool);
spin_unlock_irqrestore(&pool->lock, flags);
pool->free(element, pool->pool_data);
@@ -132,6 +132,12 @@ int mempool_resize(mempool_t *pool, int
return -ENOMEM;
spin_lock_irqsave(&pool->lock, flags);
+ if (unlikely(new_min_nr <= pool->min_nr)) {
+ /* Raced, other resize will do our work */
+ spin_unlock_irqrestore(&pool->lock, flags);
+ kfree(new_elements);
+ goto out;
+ }
memcpy(new_elements, pool->elements,
pool->curr_nr * sizeof(*new_elements));
kfree(pool->elements);
@@ -149,7 +155,7 @@ int mempool_resize(mempool_t *pool, int
} else {
spin_unlock_irqrestore(&pool->lock, flags);
pool->free(element, pool->pool_data); /* Raced */
- spin_lock_irqsave(&pool->lock, flags);
+ goto out;
}
}
out_unlock:
_