From: Jianyun Gao <[email protected]> In kset_replay, when key->seg_gen is stale (key->seg_gen < key->cache_pos.cache_seg->gen), cache_key_put(key) is called but then key->cache_pos.cache_seg is accessed as the argument to cache_seg_get(). This is a use-after-free on the freed key memory. Although mempool recycled memory is not immediately reclaimed or overwritten in practice, this is still a potential UAF bug.
Additionally, for expired invalid keys, setting the cache->seg_map bit and calling cache_seg_get() is unreasonable since the corresponding segment data is no longer valid. Fix both issues by moving cache_seg_get() and __set_bit() after the gen check, so they only execute for valid keys, and using continue to skip invalid keys. Signed-off-by: Jianyun Gao <[email protected]> --- drivers/md/dm-pcache/cache_key.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/drivers/md/dm-pcache/cache_key.c b/drivers/md/dm-pcache/cache_key.c index e068e878231b..84bad99d3fcd 100644 --- a/drivers/md/dm-pcache/cache_key.c +++ b/drivers/md/dm-pcache/cache_key.c @@ -728,18 +728,17 @@ static int kset_replay(struct pcache_cache *cache, struct pcache_cache_kset_onme goto err; } - __set_bit(key->cache_pos.cache_seg->cache_seg_id, cache->seg_map); - /* Check if the segment generation is valid for insertion. */ if (key->seg_gen < key->cache_pos.cache_seg->gen) { cache_key_put(key); - } else { - cache_subtree = get_subtree(&cache->req_key_tree, key->off); - spin_lock(&cache_subtree->tree_lock); - cache_key_insert(&cache->req_key_tree, key, true); - spin_unlock(&cache_subtree->tree_lock); + continue; } + __set_bit(key->cache_pos.cache_seg->cache_seg_id, cache->seg_map); + cache_subtree = get_subtree(&cache->req_key_tree, key->off); + spin_lock(&cache_subtree->tree_lock); + cache_key_insert(&cache->req_key_tree, key, true); + spin_unlock(&cache_subtree->tree_lock); cache_seg_get(key->cache_pos.cache_seg); } -- 2.34.1
