From: Simon Horman <horms@kernel.org>
To: Fernando Fernandez Mancera <fmancera@suse.de>
Cc: netdev@vger.kernel.org, csmate@nop.hu, kerneljasonxing@gmail.com,
maciej.fijalkowski@intel.com, bjorn@kernel.org, sdf@fomichev.me,
jonathan.lemon@gmail.com, bpf@vger.kernel.org
Subject: Re: [PATCH net] xsk: avoid data corruption on cq descriptor number
Date: Tue, 21 Oct 2025 17:25:12 +0100 [thread overview]
Message-ID: <aPez6DYh13kmY9NF@horms.kernel.org> (raw)
In-Reply-To: <20251021150656.6704-1-fmancera@suse.de>
On Tue, Oct 21, 2025 at 05:06:56PM +0200, Fernando Fernandez Mancera wrote:
...
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
...
> @@ -774,6 +777,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
> {
> struct net_device *dev = xs->dev;
> struct sk_buff *skb = xs->skb;
> + struct page *page;
> int err;
>
> if (dev->priv_flags & IFF_TX_SKB_NO_LINEAR) {
> @@ -791,6 +795,8 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
> len = desc->len;
>
> if (!skb) {
> + struct xsk_addr_node *head_addr;
> +
> hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(dev->needed_headroom));
> tr = dev->needed_tailroom;
> skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err);
> @@ -804,7 +810,13 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
> if (unlikely(err))
> goto free_err;
>
> - xsk_skb_init_misc(skb, xs, desc->addr);
> + head_addr = kmem_cache_zalloc(xsk_tx_generic_cache, GFP_KERNEL);
> + if (!head_addr) {
> + __free_page(page);
Hi Fernando,
Perhaps the page changes to xsk_build_skb() aren't needed
because page seems to be uninitialised here.
Flagged by W=1 builds with Clang 21.1.1, and Smatch.
> + err = -ENOMEM;
> + goto free_err;
> + }
> + xsk_skb_init_misc(skb, xs, head_addr, desc->addr);
> if (desc->options & XDP_TX_METADATA) {
> err = xsk_skb_metadata(skb, buffer, desc,
> xs->pool, hr);
> @@ -814,7 +826,6 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
> } else {
> int nr_frags = skb_shinfo(skb)->nr_frags;
> struct xsk_addr_node *xsk_addr;
> - struct page *page;
> u8 *vaddr;
>
> if (unlikely(nr_frags == (MAX_SKB_FRAGS - 1) && xp_mb_desc(desc))) {
> @@ -843,7 +854,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
> refcount_add(PAGE_SIZE, &xs->sk.sk_wmem_alloc);
>
> xsk_addr->addr = desc->addr;
> - list_add_tail(&xsk_addr->addr_node, &XSKCB(skb)->addrs_list);
> + list_add_tail(&xsk_addr->addr_node, &XSK_TX_HEAD(skb)->addr_node);
> }
> }
>
> --
> 2.51.0
>
>
next prev parent reply other threads:[~2025-10-21 16:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-21 15:06 [PATCH net] xsk: avoid data corruption on cq descriptor number Fernando Fernandez Mancera
2025-10-21 16:25 ` Simon Horman [this message]
2025-10-21 18:25 ` Fernando Fernandez Mancera
2025-10-22 5:23 ` kernel test robot
2025-10-22 18:24 ` Fernando Fernandez Mancera
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