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Date: Thu, 24 Sep 2026 04:16:42 +0200
From: Andrew Lunn <andrew@lunn.ch>
To: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>
Cc: Aldo Ariel Panzardo <qwe.aldo@gmail.com>, maxime.chevallier@bootlin.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org, sashiko-bot@kernel.org
Subject: Re: [PATCH] net: stmmac: guard FCS stripping against runt frames
Message-ID: <78724445-4c69-44fb-b82a-1f9275e37e9e@lunn.ch>
References: <20260923162339.1375698-1-qwe.aldo@gmail.com>
 <arQ4dVkI9llhXCDx@lore-desk>
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In-Reply-To: <arQ4dVkI9llhXCDx@lore-desk>

> > @@ -5808,10 +5809,10 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
> >  
> >  		/* ACS is disabled; strip manually. */
> >  		if (likely(!(status & rx_not_ls))) {
> > -			if (buf2_len) {
> > +			if (buf2_len >= ETH_FCS_LEN) {
> 
> I do not think this approach is correct since, at least theoretically, the FCS can be
> splitted between buf1 and buf2.

We are talking about runt frames here, so less than 64 bytes in
size. Can such a frame be split over two buffers? What is the minimum
size of the first buffer?

	Andrew