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net: gro: clear skb_shinfo(skb)->hwtstamps in napi_reuse_skb()

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Some network drivers assume this field is zero after napi_get_frags().

We must clear it in napi_reuse_skb() otherwise the following can happen:

1) A packet is received, and skb_shinfo(skb)->hwtstamps is populated
   because a bit in the receive descriptor announced hwtstamp
   availability for this packet.

2) Packet is given to gro layer via napi_gro_frags().

3) Packet is merged to a prior one held in GRO queues.

4) skb is saved after some cleanup in napi->skb via a call
   to napi_reuse_skb().

5) Next packet is received 10 seconds later, gets the recycled skb
   from napi_get_frags().

6) The receive descriptor does not announce hwtstamp availability.
   Driver does not clear shinfo->hwtstamps.

7) We have in shinfo->hwtstamps an old timestamp.

Fixes: ac45f602ee ("net: infrastructure for hardware time stamping")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://patch.msgid.link/20251015063221.4171986-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet
2025-10-15 06:32:21 +00:00
committed by Jakub Kicinski
parent aaf043a568
commit d0d3e9c286
1 changed files with 8 additions and 2 deletions
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10
net/core/gro.c
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@@ -639,6 +639,8 @@ EXPORT_SYMBOL(gro_receive_skb);
static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
{
struct skb_shared_info *shinfo;
if (unlikely(skb->pfmemalloc)) {
consume_skb(skb);
return;
@@ -655,8 +657,12 @@ static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
skb->encapsulation = 0;
skb->ip_summed = CHECKSUM_NONE;
skb_shinfo(skb)->gso_type = 0;
skb_shinfo(skb)->gso_size = 0;
shinfo = skb_shinfo(skb);
shinfo->gso_type = 0;
shinfo->gso_size = 0;
shinfo->hwtstamps.hwtstamp = 0;
if (unlikely(skb->slow_gro)) {
skb_orphan(skb);
skb_ext_reset(skb);