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From: Kalle Valo <kvalo@kernel.org>
To: Arend van Spriel <arend.vanspriel@broadcom.com>,
    Arnd Bergmann <arnd@arndb.de>
Cc: Duoming Zhou <duoming@zju.edu.cn>,  linux-kernel@vger.kernel.org,
  konrad.dybcio@linaro.org,  hdegoede@redhat.com,  minipli@grsecurity.net,
  linux-wireless@vger.kernel.org,  brcm80211@lists.linux.dev,
  brcm80211-dev-list.pdl@broadcom.com
Subject: Re: [PATCH] wifi: brcmfmac: pcie: handle randbuf allocation failure
References: <20240301135134.29577-1-duoming@zju.edu.cn>
	<fdaefac9-1d02-4424-b893-4306b97028ca@broadcom.com>
Date: Wed, 06 Mar 2024 12:53:57 +0200
In-Reply-To: <fdaefac9-1d02-4424-b893-4306b97028ca@broadcom.com> (Arend van
	Spriel's message of "Wed, 6 Mar 2024 10:19:58 +0100")
Message-ID: <87h6hjhbqy.fsf@kernel.org>
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Arend van Spriel <arend.vanspriel@broadcom.com> writes:

> On 3/1/2024 2:51 PM, Duoming Zhou wrote:
>> The kzalloc() in brcmf_pcie_download_fw_nvram() will return
>> null if the physical memory has run out. As a result, if we
>> use get_random_bytes() to generate random bytes in the randbuf,
>> the null pointer dereference bug will happen.
>> Return -ENOMEM from brcmf_pcie_download_fw_nvram() if kzalloc()
>> fails for randbuf.
>> Fixes: 91918ce88d9f ("wifi: brcmfmac: pcie: Provide a buffer of
>> random bytes to the device")
>
> Looks good to me. Looking for kernel guideline about stack usage to
> determine whether it would be ok to just use buffer on stack. Does
> anyone know. This one is 256 bytes so I guess the allocation is
> warranted here.

Arnd, what do you suggest? Do we have any documentation or guidelines
anywhere?

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