Commit a432934a authored Jul 30, 2021 by Paolo Abeni Committed by Jakub Kicinski Jul 30, 2021

sk_buff: avoid potentially clearing 'slow_gro' field



If skb_dst_set_noref() is invoked with a NULL dst, the 'slow_gro'
field is cleared, too. That could lead to wrong behavior if
the skb later enters the GRO stage.

Fix the potential issue replacing preserving a non-zero value of
the 'slow_gro' field.

Additionally, fix a comment typo.

Reported-by: Sabrina Dubroca <sd@queasysnail.net>
Reported-by: Jakub Kicinski <kuba@kernel.org>
Fixes: 8a886b14 ("sk_buff: track dst status in slow_gro")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/aa42529252dc8bb02bd42e8629427040d1058537.1627662501.git.pabeni@redhat.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent bc830525

include/linux/skbuff.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -1009,7 +1009,7 @@ static inline void skb_dst_set(struct sk_buff skb, struct dst_entry dst)
		static inline void skb_dst_set_noref(struct sk_buff skb, struct dst_entry dst)
		{
		WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
		skb->slow_gro = !!dst;
		skb->slow_gro \|= !!dst;
		skb->_skb_refdst = (unsigned long)dst \| SKB_DST_NOREF;
		}

net/core/dev.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -6022,7 +6022,7 @@ static void gro_list_prepare(const struct list_head *head,
		skb_mac_header(skb),
		maclen);

		/* in most common scenarions _state is 0
		/* in most common scenarions 'slow_gro' is 0
		* otherwise we are already on some slower paths
		* either skip all the infrequent tests altogether or
		* avoid trying too hard to skip each of them individually