From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: [Patch net] net: make pskb_trim_rcsum_slow() robust Date: Mon, 29 Oct 2018 17:35:15 -0700 Message-ID: <20181030003515.12075-1-xiyou.wangcong@gmail.com> Cc: Cong Wang , Eric Dumazet To: netdev@vger.kernel.org Return-path: Received: from mail-pg1-f194.google.com ([209.85.215.194]:36738 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725840AbeJ3JMo (ORCPT ); Tue, 30 Oct 2018 05:12:44 -0400 Received: by mail-pg1-f194.google.com with SMTP id z17-v6so4714386pgv.3 for ; Mon, 29 Oct 2018 17:21:36 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: Most callers of pskb_trim_rcsum() simply drops the skb when it fails, however, ip_check_defrag() still continues to pass the skb up to stack. In that case, we should restore its previous csum if __pskb_trim() fails. Found this during code review. Fixes: 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends") Cc: Eric Dumazet Signed-off-by: Cong Wang --- net/core/skbuff.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 946de0e24c87..5decd6e6d2b6 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1843,6 +1843,9 @@ EXPORT_SYMBOL(___pskb_trim); */ int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len) { + __wsum old_csum = skb->csum; + int ret; + if (skb->ip_summed == CHECKSUM_COMPLETE) { int delta = skb->len - len; @@ -1850,7 +1853,10 @@ int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len) skb_checksum(skb, len, delta, 0), len); } - return __pskb_trim(skb, len); + ret = __pskb_trim(skb, len); + if (unlikely(ret)) + skb->csum = old_csum; + return ret; } EXPORT_SYMBOL(pskb_trim_rcsum_slow); -- 2.16.4