netdev - Re: [PATCH v3 3/9] brcmfmac: firmware: Do not crash on a NULL board

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Date:   Wed, 19 Jan 2022 23:45:55 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Hector Martin <marcan@...can.st>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Arend van Spriel <aspriel@...il.com>,
        Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-hsien Lin <chi-hsien.lin@...ineon.com>,
        Wright Feng <wright.feng@...ineon.com>,
        Dmitry Osipenko <digetx@...il.com>,
        Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Mark Kettenis <kettenis@...nbsd.org>,
        Rafał Miłecki <zajec5@...il.com>,
        Pieter-Paul Giesberts <pieter-paul.giesberts@...adcom.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Hans de Goede <hdegoede@...hat.com>,
        "John W. Linville" <linville@...driver.com>,
        "brian m. carlson" <sandals@...stytoothpaste.net>,
        "open list:TI WILINK WIRELES..." <linux-wireless@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        "open list:BROADCOM BRCM80211 IEEE802.11n WIRELESS DRIVER" 
        <brcm80211-dev-list.pdl@...adcom.com>,
        SHA-cyfmac-dev-list@...ineon.com
Subject: Re: [PATCH v3 3/9] brcmfmac: firmware: Do not crash on a NULL board_type

On Mon, Jan 17, 2022 at 4:30 PM Hector Martin <marcan@...can.st> wrote:
>
> This unbreaks support for USB devices, which do not have a board_type
> to create an alt_path out of and thus were running into a NULL
> dereference.

In v5.16 we have two call sites:

1.
  if (cur->type == BRCMF_FW_TYPE_NVRAM && fwctx->req->board_type) {
    ...
    alt_path = brcm_alt_fw_path(cur->path, fwctx->req->board_type);

2.
  alt_path = brcm_alt_fw_path(first->path, fwctx->req->board_type);
  if (alt_path) {
    ...

Looking at them I would rather expect to see (as a quick fix, the
better solution is to unify those call sites by splitting out a common
helper):

  if (fwctx->req->board_type) {
    alt_path = brcm_alt_fw_path(first->path, fwctx->req->board_type);
  else
    alt_path = NULL;
   ...


> @@ -599,6 +599,9 @@ static char *brcm_alt_fw_path(const char *path, const char *board_type)
>         char alt_path[BRCMF_FW_NAME_LEN];
>         char suffix[5];
>
> +       if (!board_type)
> +               return NULL;


-- 
With Best Regards,
Andy Shevchenko