From: Yihao Wu <[email protected]> [ Upstream commit 43e33924c38e8faeb0c12035481cb150e602e39d ]
Deleting list entry within hlist_for_each_entry_safe is not safe unless next pointer (tmp) is protected too. It's not, because once hash_lock is released, cache_clean may delete the entry that tmp points to. Then cache_purge can walk to a deleted entry and tries to double free it. Fix this bug by holding only the deleted entry's reference. Suggested-by: NeilBrown <[email protected]> Signed-off-by: Yihao Wu <[email protected]> Reviewed-by: NeilBrown <[email protected]> [ cel: removed unused variable ] Signed-off-by: Chuck Lever <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- net/sunrpc/cache.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index bd843a81afa0b..d36cea4e270de 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -521,7 +521,6 @@ void cache_purge(struct cache_detail *detail) { struct cache_head *ch = NULL; struct hlist_head *head = NULL; - struct hlist_node *tmp = NULL; int i = 0; spin_lock(&detail->hash_lock); @@ -533,7 +532,9 @@ void cache_purge(struct cache_detail *detail) dprintk("RPC: %d entries in %s cache\n", detail->entries, detail->name); for (i = 0; i < detail->hash_size; i++) { head = &detail->hash_table[i]; - hlist_for_each_entry_safe(ch, tmp, head, cache_list) { + while (!hlist_empty(head)) { + ch = hlist_entry(head->first, struct cache_head, + cache_list); sunrpc_begin_cache_remove_entry(ch, detail); spin_unlock(&detail->hash_lock); sunrpc_end_cache_remove_entry(ch, detail); -- 2.20.1
