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

From: Arnd Bergmann
Date: Tue Jun 20 2017 - 16:41:24 EST

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.

Fixes: 030a89028db0 ("net: phy: smsc: Implement PHY statistics")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
drivers/net/phy/smsc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
index 1b8204be064c..2306bfae057f 100644
--- a/drivers/net/phy/smsc.c
+++ b/drivers/net/phy/smsc.c
@@ -163,7 +163,7 @@ static void smsc_get_strings(struct phy_device *phydev, u8 *data)
int i;

for (i = 0; i < ARRAY_SIZE(smsc_hw_stats); i++) {
- memcpy(data + i * ETH_GSTRING_LEN,
+ strncpy(data + i * ETH_GSTRING_LEN,
smsc_hw_stats[i].string, ETH_GSTRING_LEN);