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| author | Yihao Wu <wuyihao@linux.alibaba.com> | 2020-04-06 01:57:22 +0800 |
|---|---|---|
| committer | Chuck Lever <chuck.lever@oracle.com> | 2020-04-13 10:28:21 -0400 |
| commit | 43e33924c38e8faeb0c12035481cb150e602e39d (patch) | |
| tree | 2874c7b0edaf651e4804e165edf5a8c3789ca2f8 | |
| parent | e1e8399eee72e9d5246d4d1bcacd793debe34dd3 (diff) | |
| download | linux-43e33924c38e8faeb0c12035481cb150e602e39d.tar.bz2 | |
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>
| -rw-r--r-- | net/sunrpc/cache.c | 5 |
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); |