netdev - Re: [PATCH net] xsk: respect the offsets when copying frags

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7a6f896f-fade-47ed-b101-72be264dcf2b@gmail.com>
Date: Fri, 25 Apr 2025 22:46:35 +0700
From: Bui Quang Minh <minhquangbui99@...il.com>
To: netdev@...r.kernel.org
Cc: Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, "David S. Miller"
 <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Jesper Dangaard Brouer <hawk@...nel.org>,
 John Fastabend <john.fastabend@...il.com>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 Simon Horman <horms@...nel.org>,
 Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
 Alexander Lobakin <aleksander.lobakin@...el.com>, bpf@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] xsk: respect the offsets when copying frags

On 4/23/25 17:10, Bui Quang Minh wrote:
> Add the missing offsets when copying frags in xdp_copy_frags_from_zc().
>
> Fixes: 560d958c6c68 ("xsk: add generic XSk &xdp_buff -> skb conversion")
> Signed-off-by: Bui Quang Minh <minhquangbui99@...il.com>
> ---
>   net/core/xdp.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/net/core/xdp.c b/net/core/xdp.c
> index f86eedad586a..a723dc301f94 100644
> --- a/net/core/xdp.c
> +++ b/net/core/xdp.c
> @@ -697,7 +697,8 @@ static noinline bool xdp_copy_frags_from_zc(struct sk_buff *skb,
>   	nr_frags = xinfo->nr_frags;
>   
>   	for (u32 i = 0; i < nr_frags; i++) {
> -		u32 len = skb_frag_size(&xinfo->frags[i]);
> +		const skb_frag_t *frag = &xinfo->frags[i];
> +		u32 len = skb_frag_size(frag);
>   		u32 offset, truesize = len;
>   		netmem_ref netmem;
>   
> @@ -707,8 +708,8 @@ static noinline bool xdp_copy_frags_from_zc(struct sk_buff *skb,
>   			return false;
>   		}
>   
> -		memcpy(__netmem_address(netmem),
> -		       __netmem_address(xinfo->frags[i].netmem),
> +		memcpy(__netmem_address(netmem) + offset,
> +		       __netmem_address(frag->netmem) + skb_frag_off(frag),
>   		       LARGEST_ALIGN(len));
>   		__skb_fill_netmem_desc_noacc(sinfo, i, netmem, offset, len);
>   

I know it's very unlikely but do we need to 
kmap_local_page(skb_frag_page(frag) before using 
__netmem_address(frag->netmem) to make sure the frag's page is mapped? 
Or it is impossible that the frag's page to be highmem and unmapped? Thanks,
Quang Minh.