Subject: Re: [PATCH] net: phy: smsc: fix buffer overflow in memcpy

From: Andrew Lunn <[email-masked]>
Date: Tue, 20 Jun 2017 23:46:15 +0200

On Tue, Jun 20, 2017 at 10:40:46PM +0200, Arnd Bergmann wrote:
> The memcpy annotation triggers for a fixed-length buffer copy:
> 
> In file included from /git/arm-soc/arch/arm64/include/asm/processor.h:30:0,
>                  from /git/arm-soc/arch/arm64/include/asm/spinlock.h:21,
>                  from /git/arm-soc/include/linux/spinlock.h:87,
>                  from /git/arm-soc/include/linux/seqlock.h:35,
>                  from /git/arm-soc/include/linux/time.h:5,
>                  from /git/arm-soc/include/linux/stat.h:21,
>                  from /git/arm-soc/include/linux/module.h:10,
>                  from /git/arm-soc/drivers/net/phy/smsc.c:20:
> In function 'memcpy',
>     inlined from 'smsc_get_strings' at /git/arm-soc/drivers/net/phy/smsc.c:166:3:
> /git/arm-soc/include/linux/string.h:309:4: error: call to '__read_overflow2' declared with attribute error: detected read beyond size of object passed as 2nd parameter
> 
> Using strncpy instead of memcpy should do the right thing here.

Hi Arnd

You will find this pattern in number of phy drivers:

bcm-phy-lib.c:	   	   memcpy(data + i * ETH_GSTRING_LEN,
marvell.c:			       		   memcpy(data + i * ETH_GSTRING_LEN,
micrel.c:   		memcpy(data + i * ETH_GSTRING_LEN,
smsc.c:				    memcpy(data + i * ETH_GSTRING_LEN,

They probably all need the same fix.

     Andrew