linux-kernel - Re: [PATCH] kalmia: avoid potential uninitialized variable use

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Message-Id: <20161027.162806.122471124625949377.davem@davemloft.net>
Date:   Thu, 27 Oct 2016 16:28:06 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     arnd@...db.de
Cc:     netdev@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kalmia: avoid potential uninitialized variable use

From: Arnd Bergmann <arnd@...db.de>
Date: Mon, 24 Oct 2016 17:54:18 +0200

> The kalmia_send_init_packet() returns zero or a negative return
> code, but gcc has no way of knowing that there cannot be a
> positive return code, so it determines that copying the ethernet
> address at the end of kalmia_bind() will access uninitialized
> data:
> 
> drivers/net/usb/kalmia.c: In function ‘kalmia_bind’:
> arch/x86/include/asm/string_32.h:78:22: error: ‘*((void *)&ethernet_addr+4)’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>    *((short *)to + 2) = *((short *)from + 2);
>                       ^
> drivers/net/usb/kalmia.c:138:5: note: ‘*((void *)&ethernet_addr+4)’ was declared here
> 
> This warning is harmless, but for consistency, we should make
> the check for the return code match what the driver does everywhere
> else and just progate it, which then gets rid of the warning.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Applied, thanks.