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Commit fff88030 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
Browse files

skbuff: only inherit relevant tx_flags 



When inheriting tx_flags from one skbuff to another, always apply a
mask to avoid overwriting unrelated other bits in the field.

The two SKBTX_SHARED_FRAG cases clears all other bits. In practice,
tx_flags are zero at this point now. But this is fragile. Timestamp
flags are set, for instance, if in tcp_gso_segment, after this clear
in skb_segment.

The SKBTX_ANY_TSTAMP mask in __skb_tstamp_tx ensures that new
skbs do not accidentally inherit flags such as SKBTX_SHARED_FRAG.

Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 50430d1f

net/core/skbuff.c

+6 −4
Original line number Diff line number Diff line
@@ -2646,7 +2646,8 @@ void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len) 
{

	int pos = skb_headlen(skb);



	skb_shinfo(skb1)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;

	skb_shinfo(skb1)->tx_flags |= skb_shinfo(skb)->tx_flags &

				      SKBTX_SHARED_FRAG;

	if (len < pos)	/* Split line is inside header. */

		skb_split_inside_header(skb, skb1, len, pos);

	else		/* Second chunk has no header, nothing to copy. */
@@ -3261,7 +3262,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, 
		skb_copy_from_linear_data_offset(head_skb, offset,

						 skb_put(nskb, hsize), hsize);



		skb_shinfo(nskb)->tx_flags = skb_shinfo(head_skb)->tx_flags &

		skb_shinfo(nskb)->tx_flags |= skb_shinfo(head_skb)->tx_flags &

					      SKBTX_SHARED_FRAG;



		while (pos < offset + len) {
@@ -3948,7 +3949,8 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, 
		return;



	if (tsonly) {

		skb_shinfo(skb)->tx_flags = skb_shinfo(orig_skb)->tx_flags;

		skb_shinfo(skb)->tx_flags |= skb_shinfo(orig_skb)->tx_flags &

					     SKBTX_ANY_TSTAMP;

		skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;

	}