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authorYihao Wu <wuyihao@linux.alibaba.com>2020-04-06 01:57:22 +0800
committerChuck Lever <chuck.lever@oracle.com>2020-04-13 10:28:21 -0400
commit43e33924c38e8faeb0c12035481cb150e602e39d (patch)
tree2874c7b0edaf651e4804e165edf5a8c3789ca2f8 /net/sunrpc/cache.c
parente1e8399eee72e9d5246d4d1bcacd793debe34dd3 (diff)
SUNRPC/cache: Fix unsafe traverse caused double-free in cache_purge
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 <neilb@suse.de> Signed-off-by: Yihao Wu <wuyihao@linux.alibaba.com> Reviewed-by: NeilBrown <neilb@suse.de> [ cel: removed unused variable ] Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'net/sunrpc/cache.c')
-rw-r--r--net/sunrpc/cache.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index af0ddd28b081..baef5ee43dbb 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -529,7 +529,6 @@ 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);
@@ -541,7 +540,9 @@ 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);