path: root/net
diff options
authorTung Nguyen <tung.q.nguyen@dektech.com.au>2020-10-27 10:24:03 +0700
committerJakub Kicinski <kuba@kernel.org>2020-10-29 09:51:52 -0700
commitceb1eb2fb609c88363e06618b8d4bbf7815a4e03 (patch)
tree8fbfc66d7f4a141c865ede1f52f1c32477fc33ba /net
parent51467431200b91682b89d31317e35dcbca1469ce (diff)
tipc: fix memory leak caused by tipc_buf_append()
Commit ed42989eab57 ("tipc: fix the skb_unshare() in tipc_buf_append()") replaced skb_unshare() with skb_copy() to not reduce the data reference counter of the original skb intentionally. This is not the correct way to handle the cloned skb because it causes memory leak in 2 following cases: 1/ Sending multicast messages via broadcast link The original skb list is cloned to the local skb list for local destination. After that, the data reference counter of each skb in the original list has the value of 2. This causes each skb not to be freed after receiving ACK: tipc_link_advance_transmq() { ... /* release skb */ __skb_unlink(skb, &l->transmq); kfree_skb(skb); <-- memory exists after being freed } 2/ Sending multicast messages via replicast link Similar to the above case, each skb cannot be freed after purging the skb list: tipc_mcast_xmit() { ... __skb_queue_purge(pkts); <-- memory exists after being freed } This commit fixes this issue by using skb_unshare() instead. Besides, to avoid use-after-free error reported by KASAN, the pointer to the fragment is set to NULL before calling skb_unshare() to make sure that the original skb is not freed after freeing the fragment 2 times in case skb_unshare() returns NULL. Fixes: ed42989eab57 ("tipc: fix the skb_unshare() in tipc_buf_append()") Acked-by: Jon Maloy <jmaloy@redhat.com> Reported-by: Thang Hoang Ngo <thang.h.ngo@dektech.com.au> Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au> Reviewed-by: Xin Long <lucien.xin@gmail.com> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Link: https://lore.kernel.org/r/20201027032403.1823-1-tung.q.nguyen@dektech.com.au Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
1 files changed, 2 insertions, 3 deletions
diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index 2a78aa701572..32c79c59052b 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -150,12 +150,11 @@ int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf)
if (fragid == FIRST_FRAGMENT) {
if (unlikely(head))
goto err;
- if (skb_cloned(frag))
- frag = skb_copy(frag, GFP_ATOMIC);
+ *buf = NULL;
+ frag = skb_unshare(frag, GFP_ATOMIC);
if (unlikely(!frag))
goto err;
head = *headbuf = frag;
- *buf = NULL;
TIPC_SKB_CB(head)->tail = NULL;
if (skb_is_nonlinear(head)) {
skb_walk_frags(head, tail) {