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

From: Kalle Valo
Date: Tue Sep 28 2021 - 02:43:45 EST


Arnd Bergmann <arnd@xxxxxxxxxx> writes:

> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> 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@xxxxxxxx>

I'll queue this to v5.15.

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