From 088f160d6f6dc06cf858e864ba8e81548387af1e Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Tue, 27 Jul 2021 15:56:50 -0700 Subject: [PATCH] tipc: Fix backport of b77413446408fdd256599daf00d5be72b5f3e7c6 Clang warns: net/tipc/link.c:896:23: warning: variable 'hdr' is uninitialized when used here [-Wuninitialized] imp = msg_importance(hdr); ^~~ net/tipc/link.c:890:22: note: initialize the variable 'hdr' to silence this warning struct tipc_msg *hdr; ^ = NULL 1 warning generated. The backport of commit b77413446408 ("tipc: fix NULL deref in tipc_link_xmit()") to 4.9 as commit 310014f572a5 ("tipc: fix NULL deref in tipc_link_xmit()") added the hdr initialization above the if (unlikely(msg_size(hdr) > mtu)) { like in the upstream commit; however, in 4.9, that check is below imp's first use because commit 365ad353c256 ("tipc: reduce risk of user starvation during link congestion") is not present. This results in hdr being used uninitialized. Fix this by moving hdr's initialization before imp and after the if check like the original backport did. Cc: Hoang Le Cc: Jon Maloy Cc: Ying Xue Fixes: 310014f572a5 ("tipc: fix NULL deref in tipc_link_xmit()") Reported-by: kernel test robot Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman --- net/tipc/link.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/tipc/link.c b/net/tipc/link.c index 06327f78f203..6fc2fa75503d 100644 --- a/net/tipc/link.c +++ b/net/tipc/link.c @@ -893,6 +893,7 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list, if (pkt_cnt <= 0) return 0; + hdr = buf_msg(skb_peek(list)); imp = msg_importance(hdr); /* Match msg importance against this and all higher backlog limits: */ if (!skb_queue_empty(backlogq)) { @@ -902,7 +903,6 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list, } } - hdr = buf_msg(skb_peek(list)); if (unlikely(msg_size(hdr) > mtu)) { skb_queue_purge(list); return -EMSGSIZE; -- 2.20.1