From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ixit.cz (ixit.cz [84.42.129.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BB2073F210A for ; Sun, 20 Sep 2026 23:02:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=84.42.129.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789945354; cv=none; b=vELMH3uMvvUI9adQ64sLxVpcwdNBMDXRLJNJrog78o+FnBlqnWw1hhFUaq6IHPbu2y/1wnIDAJM3psqimh5PulyVI3PqiAqIfTFFw6N1Y4e4uPUZ6ZKlTp+JO/iL9T0pniE2XSJdyPHxSlWlKttvog3C/NQl7epSpeeeLO6bHkc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789945354; c=relaxed/simple; bh=ihjoM7D2BcOiPrTy053asAyX+JgsRpLuEQH6m2offlA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ktjxm13x/Thj5rryQNCDk1LM6E94Q0YbTIbC4OJObizfBxSGFbAfPzF5NuPPU802iXiDuWZWhWMPwVGCn34E/8MMBizfoarJU3EnBPGnLS4+sFzE8N6TflvinRHCfXnA6kODdSekaJjnSVOyKbhaDp1Ej0PTfRCLDTo/j6tCkqk= ARC-Authentication-Results:i=1; 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t=1789945350; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=1b2TOb7Uz4K71IwXM8bB3TJBDyr028aAuvtvwxg4Lt4=; b=Mm4IiGGe6LtAx7w+iUPjgvZPobBhhRiOiDEpGKcAxMfCGvAPZzEWyf+p9TgyA9U7Q9Cp7W eO/Cekk6HxoMq9wU9RTQeo9qAquwmyVF25KbUHd+uZ0m2qAePjd58djyRoFc70C6ffPRqt TCofY1uBH7/9BW0RfOFy+W5IvqamdQw= Message-ID: Date: Mon, 21 Sep 2026 01:02:29 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] nfc: st95hf: validate device-reported response length before reading To: Tianchu Chen , sameo@linux.intel.com, shikha.singh@st.com Cc: oe-linux-nfc@lists.linux.dev, linux-kernel@vger.kernel.org References: <91f49a98dd42655829b7206f0d64cc31ef9c0e95@linux.dev> Content-Language: en-US, cs-CZ From: David Heidelberg Autocrypt: addr=david@ixit.cz; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 19/08/2026 16:55, Tianchu Chen wrote: > From: Tianchu Chen > > st95hf_spi_recv_response() reads a 2-byte header from the device, > derives the total response length from it (up to 1025 bytes via the > long-frame encoding) and then blindly reads len - 2 more bytes into > the caller's buffer, whose size it knows nothing about. > > Call sites can be overflowed by a device reporting a large length, > for example, st95hf_irq_thread_handler() passes the data area of a > 280-byte skb. > > ST95HF datasheet states "In Reader mode it is possible to receive up to > 528 bytes of frame data from VICC and TypeB cards", so technically a bogus > NFC tag may trigger the OOB-write if the card-reader's firmware allows > large packets. > > Add a buff_len parameter and reject a device-reported length that does > not fit into the caller's buffer before issuing the second SPI > transfer. Also modify callers to pass their real buffer sizes. > > Discovered by Atuin - Automated Vulnerability Discovery Engine. > > Fixes: cab47333f0f75 ("NFC: Add STMicroelectronics ST95HF driver") > Cc: stable@vger.kernel.org > Signed-off-by: Tianchu Chen > --- > drivers/nfc/st95hf/core.c | 6 ++++-- > drivers/nfc/st95hf/spi.c | 7 ++++++- > drivers/nfc/st95hf/spi.h | 2 +- > 3 files changed, 11 insertions(+), 4 deletions(-) > Hello Tianchu, please check and address the Sashiko output. Thank you David [ ... ] > @@ -106,6 +106,11 @@ int st95hf_spi_recv_response(struct st95hf_spi_context *spicontext, > else > len += receivebuff[1]; > > + if (len > buff_len) { > + mutex_unlock(&spicontext->spi_lock); > + return -E2BIG; > + } > + Does this early return path leave the spi chip select (CS) permanently asserted? The first spi transfer uses .cs_change = 1 to keep the chip select active. Skipping the second transfer would prevent the chip select from being deasserted, potentially deadlocking the device. > /* Now make a transfer to read only relevant bytes */ > tx_takedata.rx_buf = &receivebuff[2]; > tx_takedata.len = len - 2;