Re: [PATCH] wifi: brcmfmac: Fix field-spanning write in brcmf_scan_params_v2_to_v1()

[Kalle Valo <kvalo@kernel.org>]

Hans de Goede <hdegoede@redhat.com> writes:

> Hi,
>
> On 8/1/23 16:37, Kalle Valo wrote:
>> Hans de Goede <hdegoede@redhat.com> wrote:
>> 
>>> Using brcmfmac with 6.5-rc3 on a brcmfmac43241b4-sdio triggers
>>> a backtrace caused by the following field-spanning error:
>>>
>>> memcpy: detected field-spanning write (size 120) of single field
>>>   "&params_le->channel_list[0]" at
>>>   drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1072 (size 2)
>>>
>>> Fix this by replacing the channel_list[1] declaration at the end of
>>> the struct with a flexible array declaration.
>>>
>>> Most users of struct brcmf_scan_params_le calculate the size to alloc
>>> using the size of the non flex-array part of the struct + needed extra
>>> space, so they do not care about sizeof(struct brcmf_scan_params_le).
>>>
>>> brcmf_notify_escan_complete() however uses the struct on the stack,
>>> expecting there to be room for at least 1 entry in the channel-list
>>> to store the special -1 abort channel-id.
>>>
>>> To make this work use an anonymous union with a padding member
>>> added + the actual channel_list flexible array.
>>>
>>> Cc: Kees Cook <keescook@chromium.org>
>>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>>> Reviewed-by: Kees Cook <keescook@chromium.org>
>> 
>> Does the driver still work even if this warning is printed? I'm wondering
>> should I take this to wireless or wireless-next. Also a review from Broadcom
>> would be really good.
>
> It works fine, but it logs an oops / backtrace.

I'll add that info to the commit log.

> Note I did test the patch on a device where the warning was triggered
> and the warning is gone and wifi association still works.
>
> So there is a slight preference to get this as a fix into 6.5 from my side.

I'll queue this wireless then. But I really would like to Broadcom take
a look at this in case we are missing something.

>> What about a Fixes tag? 
>
> This is caused by the new field-spanning wtire checks enabled
> recently, so there is not really a brcmfmac commit to point to as the
> culprit.

Ok.

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