skbuff: only inherit relevant tx_flags (fff88030) · Commits · 戴 / test

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:

Willem de Bruijn <willemb@google.com> Acked-by:

Soheil Hassas Yeganeh <soheil@google.com> Acked-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

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 @@ normal:
		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;
		}

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