netdev - Re: [PATCH] mwifiex: avoid null-pointer-subtraction warning

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Date:   Tue, 28 Sep 2021 09:43:32 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Amitkumar Karwar <amitkarwar@...il.com>,
        Ganapathi Bhat <ganapathi017@...il.com>,
        Sharvari Harisangam <sharvari.harisangam@....com>,
        Xinming Hu <huxinming820@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] mwifiex: avoid null-pointer-subtraction warning

Arnd Bergmann <arnd@...nel.org> writes:

> From: Arnd Bergmann <arnd@...db.de>
>
> clang complains about some NULL pointer arithmetic in this driver:
>
> drivers/net/wireless/marvell/mwifiex/sta_tx.c:65:59: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
>         pad = ((void *)skb->data - (sizeof(*local_tx_pd) + hroom)-
>                                                                  ^
> drivers/net/wireless/marvell/mwifiex/uap_txrx.c:478:53: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
>         pad = ((void *)skb->data - (sizeof(*txpd) + hroom) - NULL) &
>
> Rework that expression to do the same thing using a uintptr_t.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

I'll queue this to v5.15.

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