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Subject: Re: wifi: brcmfmac: Fix field-spanning write in
 brcmf_scan_params_v2_to_v1()
From:   Kalle Valo <kvalo@kernel.org>
In-Reply-To: <20230729140500.27892-1-hdegoede@redhat.com>
References: <20230729140500.27892-1-hdegoede@redhat.com>
To:     Hans de Goede <hdegoede@redhat.com>
Cc:     Arend van Spriel <aspriel@gmail.com>,
        Franky Lin <franky.lin@broadcom.com>,
        Hante Meuleman <hante.meuleman@broadcom.com>,
        Hans de Goede <hdegoede@redhat.com>,
        linux-wireless@vger.kernel.org,
        brcm80211-dev-list.pdl@broadcom.com,
        SHA-cyfmac-dev-list@infineon.com, Kees Cook <keescook@chromium.org>
User-Agent: pwcli/0.1.1-git (https://github.com/kvalo/pwcli/) Python/3.11.2
Message-ID: <169097250604.345979.80300613431075820.kvalo@kernel.org>
Date:   Wed,  2 Aug 2023 10:35:07 +0000 (UTC)
Precedence: bulk

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 warning:
> 
> 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)
> 
> The driver still works after this warning. The warning was introduced by the
> new field-spanning write checks which were enabled recently.
> 
> 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>
> Reviewed-by: Franky Lin <franky.lin@broadcom.com>

Patch applied to wireless.git, thanks.

16e455a465fc wifi: brcmfmac: Fix field-spanning write in brcmf_scan_params_v2_to_v1()

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20230729140500.27892-1-hdegoede@redhat.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches