netdev - RE: [Intel-wired-lan] [PATCH net v2 1/2] stmmac: xsk: fix underflow of budget in zerocopy mode

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: <PH3PPF7A88A980A84F2194C6E1E941DDE80E55CA@PH3PPF7A88A980A.namprd11.prod.outlook.com>
Date: Tue, 22 Jul 2025 15:03:45 +0000
From: "Loktionov, Aleksandr" <aleksandr.loktionov@...el.com>
To: Jason Xing <kerneljasonxing@...il.com>, "Nguyen, Anthony L"
	<anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
	<przemyslaw.kitszel@...el.com>, "andrew+netdev@...n.ch"
	<andrew+netdev@...n.ch>, "davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"bjorn@...nel.org" <bjorn@...nel.org>, "Karlsson, Magnus"
	<magnus.karlsson@...el.com>, "Fijalkowski, Maciej"
	<maciej.fijalkowski@...el.com>, "jonathan.lemon@...il.com"
	<jonathan.lemon@...il.com>, "sdf@...ichev.me" <sdf@...ichev.me>,
	"ast@...nel.org" <ast@...nel.org>, "daniel@...earbox.net"
	<daniel@...earbox.net>, "hawk@...nel.org" <hawk@...nel.org>,
	"john.fastabend@...il.com" <john.fastabend@...il.com>,
	"mcoquelin.stm32@...il.com" <mcoquelin.stm32@...il.com>,
	"alexandre.torgue@...s.st.com" <alexandre.torgue@...s.st.com>
CC: "linux-stm32@...md-mailman.stormreply.com"
	<linux-stm32@...md-mailman.stormreply.com>, "bpf@...r.kernel.org"
	<bpf@...r.kernel.org>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, Jason Xing <kernelxing@...cent.com>
Subject: RE: [Intel-wired-lan] [PATCH net v2 1/2] stmmac: xsk: fix underflow
 of budget in zerocopy mode



> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf
> Of Jason Xing
> Sent: Tuesday, July 22, 2025 3:51 PM
> To: Nguyen, Anthony L <anthony.l.nguyen@...el.com>; Kitszel,
> Przemyslaw <przemyslaw.kitszel@...el.com>; andrew+netdev@...n.ch;
> davem@...emloft.net; edumazet@...gle.com; kuba@...nel.org;
> pabeni@...hat.com; bjorn@...nel.org; Karlsson, Magnus
> <magnus.karlsson@...el.com>; Fijalkowski, Maciej
> <maciej.fijalkowski@...el.com>; jonathan.lemon@...il.com;
> sdf@...ichev.me; ast@...nel.org; daniel@...earbox.net;
> hawk@...nel.org; john.fastabend@...il.com; mcoquelin.stm32@...il.com;
> alexandre.torgue@...s.st.com
> Cc: linux-stm32@...md-mailman.stormreply.com; bpf@...r.kernel.org;
> intel-wired-lan@...ts.osuosl.org; netdev@...r.kernel.org; Jason Xing
> <kernelxing@...cent.com>
> Subject: [Intel-wired-lan] [PATCH net v2 1/2] stmmac: xsk: fix
> underflow of budget in zerocopy mode
> 
> From: Jason Xing <kernelxing@...cent.com>
> 
> An underflow can happen when the budget number of descs are consumed.
> as long as the budget is decreased to zero, it will again go into
> while (budget-- > 0) statement and get decreased by one, so the
> underflow issue can happen. It will lead to returning true whereas the
> expected value should be false.
> 
> In this case where all the budget is used up, it means zc function
> should return false to let the poll run again because normally we
> might have more data to process. Without this patch, zc function would
> return true instead.
> 
> Fixes: 132c32ee5bc0 ("net: stmmac: Add TX via XDP zero-copy socket")
> Signed-off-by: Jason Xing <kernelxing@...cent.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@...el.com>
> ---
> v2
> Link: https://lore.kernel.org/all/20250721083343.16482-1-
> kerneljasonxing@...il.com/
> 1. target net tree instead of net-next
> 2. revise commit message
> 3. use for loop to replace while loop
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index f350a6662880..c4cd4526ba05 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -2596,7 +2596,7 @@ static bool stmmac_xdp_xmit_zc(struct
> stmmac_priv *priv, u32 queue, u32 budget)
> 
>  	budget = min(budget, stmmac_tx_avail(priv, queue));
> 
> -	while (budget-- > 0) {
> +	for (; budget > 0; budget--)
>  		struct stmmac_metadata_request meta_req;
>  		struct xsk_tx_metadata *meta = NULL;
>  		dma_addr_t dma_addr;
> --
> 2.41.3