From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 47EAA149C45; Mon, 5 Aug 2024 08:20:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722846020; cv=none; b=aT31cBxX6Jks9eMyroFYY5tmCWbNXWqkPI90C/4sVIK/wCYPBRFHstO430Poydz5mHjXHEMooYozlc6CQDkYCQTzIReWQ6Wx+REbR7/+vfS/tXUq4OQzwabGuU6ruxq8gn/gkI9rhA7F36MTxcE7+0xnBMM+ynaZrZt2aKy8B48= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722846020; c=relaxed/simple; bh=wmW9uKSb/2SP16SrvbJjH83JY/E4lBeMVQe2z/6uRjA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=OMVhoUixshh+iKXIGU2jSDHEkoAcVeXFsZ2/seJ9L5g3MwDFirATCOCY0eHtBjKxYwLT9/iFgDZB615FDzQvfbH4o72nnyzxmL7z28Xm2bFH1d/r+GWuOTk2U4H52soRUF7/YZN7g2U24V4mLIrtQBs5S4Mvp+bV6O5dztzxRzw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=K2JhqSMw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="K2JhqSMw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51C2FC32782; Mon, 5 Aug 2024 08:20:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722846019; bh=wmW9uKSb/2SP16SrvbJjH83JY/E4lBeMVQe2z/6uRjA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=K2JhqSMwwZ8/QOqbW2z24A69QE2LKeq77pogtoozix5anJLdQzeonjm2LoPajQfIZ nqylIoAZzEh09TD54hvDIXt1C0v+ACyuPfec/M2c4o8RdA2g0w8SHwpIkjbYN9xMnB er+6CkbjyitB5FnDChNaVg+2wcRPoXlQUDkAib2plzLHjl4STJzIEcZ9D3zIKmRRfS /ztT+v6XTT/RUZsAICzX46uChxYO8yWjOxESCw5FfQ/z8AGVDJkyby36Nr9ZyR+884 razxShdh6YS4V/Hq3hEquRjIFvfvGw944WXMlvpnjRIb0pEnCXlWNTu2VbBRVhzCs4 nmcqHa9JxDULw== Message-ID: Date: Mon, 5 Aug 2024 10:20:14 +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: nci: Fix uninit-value in nci_rx_work() To: Simon Horman , zhanghao Cc: bongsu.jeon@samsung.com, syzbot+3da70a0abd7f5765b6ea@syzkaller.appspotmail.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org References: <20240803121817.383567-1-zhanghao1@kylinos.cn> <20240804105716.GA2581863@kernel.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 04/08/2024 12:57, Simon Horman wrote: > On Sat, Aug 03, 2024 at 08:18:17PM +0800, zhanghao wrote: >> Commit e624e6c3e777 ("nfc: Add a virtual nci device driver") >> calls alloc_skb() with GFP_KERNEL as the argument flags.The >> allocated heap memory was not initialized.This causes KMSAN >> to detect an uninitialized value. >> >> Reported-by: syzbot+3da70a0abd7f5765b6ea@syzkaller.appspotmail.com >> Closes: https://syzkaller.appspot.com/bug?extid=3da70a0abd7f5765b6ea > > Hi, > > I wonder if the problem reported above is caused by accessing packet > data which is past the end of what is copied in virtual_ncidev_write(). > I.e. count is unusually short and this is not being detected. > >> Fixes: e624e6c3e777 ("nfc: Add a virtual nci device driver") >> Link: https://lore.kernel.org/all/000000000000747dd6061a974686@google.com/T/ >> Signed-off-by: zhanghao >> --- >> drivers/nfc/virtual_ncidev.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/nfc/virtual_ncidev.c b/drivers/nfc/virtual_ncidev.c >> index 6b89d596ba9a..ae1592db131e 100644 >> --- a/drivers/nfc/virtual_ncidev.c >> +++ b/drivers/nfc/virtual_ncidev.c >> @@ -117,7 +117,7 @@ static ssize_t virtual_ncidev_write(struct file *file, >> struct virtual_nci_dev *vdev = file->private_data; >> struct sk_buff *skb; >> >> - skb = alloc_skb(count, GFP_KERNEL); >> + skb = alloc_skb(count, GFP_KERNEL|__GFP_ZERO); >> if (!skb) >> return -ENOMEM; > > I'm not sure this helps wrt initialising the memory as immediately below there > is; > > if (copy_from_user(skb_put(skb, count), buf, count)) { > ... > > Which I assume will initialise count bytes of skb data. Yeah, this looks like hiding the real issue. Best regards, Krzysztof