Subject: Re: [PATCH v5.15.205] ipv4: set SKBFL_SHARED_FRAG in the right skb field

From: Qingfang Deng <[email-masked]>
Date: Sat, 9 May 2026 14:13:50 +0800

On Sat, 9 May 2026 at 13:37:51 +0800, Feng Zhou wrote:
> 
> commit ab8b995323e5237041472d07e5055f5f7dcdf15b
> ("xfrm: esp: avoid in-place decrypt on shared skb frags")
> backported the shared frag marking to ip_append_page(), but it writes
> SKBFL_SHARED_FRAG to skb_shinfo(skb)->tx_flags.
> 
> SKBFL_SHARED_FRAG is a skb_shared_info::flags bit, so storing it in
> skb_shinfo(skb)->tx_flags does not mark the skb as carrying shared
> frags for later consumers.
> 
> Set the bit in skb_shinfo(skb)->flags instead. This makes the
> backport actually tag spliced UDP pages as shared and restores the
> protection intended for the ESP-in-UDP path.
> 
> Fixes: ab8b995323e5237041472d07e5055f5f7dcdf15b ("xfrm: esp: avoid in-place decrypt on shared skb frags")
> Signed-off-by: Feng Zhou <[email-masked]>

Duplicate of commit fe785bb3a809.

FYI, stable patches should be sent to [email-masked].

Regards,
Qingfang