linux-kernel - [PATCH] net: add missing skb_uarg refcount increment in pskb_carve_inside

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Date:   Thu, 13 Aug 2020 08:13:10 -0400
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <davem@...emloft.net>, <kuba@...nel.org>, <fw@...len.de>,
        <martin.varghese@...ia.com>, <pshelar@....org>,
        <dcaratti@...hat.com>, <edumazet@...gle.com>,
        <steffen.klassert@...unet.com>, <pabeni@...hat.com>,
        <shmulik@...anetworks.com>, <kyk.segfault@...il.com>,
        <sowmini.varadhan@...cle.com>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH] net: add missing skb_uarg refcount increment in pskb_carve_inside_header()

If the skb is zcopied, we should increase the skb_uarg refcount before we
involve skb_release_data(). See pskb_expand_head() as a reference.

Fixes: 6fa01ccd8830 ("skbuff: Add pskb_extract() helper function")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 net/core/skbuff.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 475f9aa51b57..975600558e8b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5842,6 +5842,8 @@ static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
 			kfree(data);
 			return -ENOMEM;
 		}
+		if (skb_zcopy(skb))
+			refcount_inc(&skb_uarg(skb)->refcnt);
 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
 			skb_frag_ref(skb, i);
 		if (skb_has_frag_list(skb))
-- 
2.19.1