Patch "skbuff: only inherit relevant tx_flags" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    skbuff: only inherit relevant tx_flags

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     skbuff-only-inherit-relevant-tx_flags.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Apr 10 10:31:53 CEST 2018
From: Willem de Bruijn <willemb@google.com>
Date: Thu, 8 Jun 2017 11:35:03 -0400
Subject: skbuff: only inherit relevant tx_flags

From: Willem de Bruijn <willemb@google.com>


[ Upstream commit fff88030b3ff930ca7a3d74acfee0472f33887ea ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/skbuff.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2551,7 +2551,8 @@ void skb_split(struct sk_buff *skb, stru
 {
 	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. */
@@ -3115,8 +3116,8 @@ struct sk_buff *skb_segment(struct sk_bu
 		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 &
-			SKBTX_SHARED_FRAG;
+		skb_shinfo(nskb)->tx_flags |= skb_shinfo(head_skb)->tx_flags &
+					      SKBTX_SHARED_FRAG;
 
 		while (pos < offset + len) {
 			if (i >= nfrags) {
@@ -3734,7 +3735,8 @@ void __skb_tstamp_tx(struct sk_buff *ori
 		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;
 	}
 


Patches currently in stable-queue which might be from willemb@google.com are

queue-4.4/skbuff-only-inherit-relevant-tx_flags.patch