netdev - [PATCH net] skbuff: Unconditionally copy pfmemalloc in __skb

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Date:   Fri, 13 Jul 2018 13:21:07 +0200
From:   Stefano Brivio <sbrivio@...hat.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     Sabrina Dubroca <sd@...asysnail.net>, Mel Gorman <mgorman@...e.de>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Patrick Talbert <ptalbert@...hat.com>, netdev@...r.kernel.org
Subject: [PATCH net] skbuff: Unconditionally copy pfmemalloc in __skb_clone()

Commit 8b7008620b84 ("net: Don't copy pfmemalloc flag in
__copy_skb_header()") introduced a different handling for the
pfmemalloc flag in copy and clone paths.

In __skb_clone(), now, the flag is set only if it was set in the
original skb, but not cleared if it wasn't. This is wrong and
might lead to socket buffers being flagged with pfmemalloc even
if the skb data wasn't allocated from pfmemalloc reserves. Copy
the flag instead of ORing it.

Reported-by: Sabrina Dubroca <sd@...asysnail.net>
Fixes: 8b7008620b84 ("net: Don't copy pfmemalloc flag in __copy_skb_header()")
Signed-off-by: Stefano Brivio <sbrivio@...hat.com>
---
 net/core/skbuff.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4df3164bb5fc..8e51f8555e11 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -858,8 +858,7 @@ static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
 	n->cloned = 1;
 	n->nohdr = 0;
 	n->peeked = 0;
-	if (skb->pfmemalloc)
-		n->pfmemalloc = 1;
+	C(pfmemalloc);
 	n->destructor = NULL;
 	C(tail);
 	C(end);
-- 
2.15.1