[PATCH v2 0/4] net: Use strlcpy() for ethtool::get_strings

Hi all,

After turning on KASAN on one of my systems, I started getting lots of out of
bounds errors while fetching a given port's statistics, and indeed using
memcpy() is unsafe for copying strings which have not been declared as an array
of ETH_GSTRING_LEN bytes, so let's use strlcpy() instead. This allows the best
of both worlds: we still keep the efficient memory usage of variably sized
strings, but we don't copy more than we need to.

Changes in v2:
- dropped the 3 other patches that were not necessary
- use strlcpy() instead of strncpy()

Florian Fainelli (4):
  net: dsa: b53: Use strlcpy() for ethtool::get_strings
  net: phy: marvell: Use strlcpy() for ethtool::get_strings
  net: phy: micrel: Use strlcpy() for ethtool::get_strings
  net: phy: broadcom: Use strlcpy() for ethtool::get_strings

 drivers/net/dsa/b53/b53_common.c | 4 ++--
 drivers/net/phy/bcm-phy-lib.c    | 4 ++--
 drivers/net/phy/marvell.c        | 4 ++--
 drivers/net/phy/micrel.c         | 4 ++--
 4 files changed, 8 insertions(+), 8 deletions(-)

-- 
2.14.1

Our statistics strings are allocated at initialization without being
bound to a specific size, yet, we would copy ETH_GSTRING_LEN bytes using
memcpy() which would create out of bounds accesses, this was flagged by
KASAN. Replace this with strlcpy() to make sure we are bound the source
buffer size and we also always NUL-terminate strings.

Fixes: 967dd82ffc52 ("net: dsa: b53: Add support for Broadcom RoboSwitch")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/net/dsa/b53/b53_common.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index db830a1141d9..63e02a54d537 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c

@@ -814,8 +814,8 @@ void b53_get_strings(struct dsa_switch *ds, int port, uint8_t *data)
 	unsigned int i;
 
 	for (i = 0; i < mib_size; i++)
-		memcpy(data + i * ETH_GSTRING_LEN,
-		       mibs[i].name, ETH_GSTRING_LEN);
+		strlcpy(data + i * ETH_GSTRING_LEN,
+			mibs[i].name, ETH_GSTRING_LEN);
 }
 EXPORT_SYMBOL(b53_get_strings);
 

-- 
2.14.1

Our statistics strings are allocated at initialization without being
bound to a specific size, yet, we would copy ETH_GSTRING_LEN bytes using
memcpy() which would create out of bounds accesses, this was flagged by
KASAN. Replace this with strlcpy() to make sure we are bound the source
buffer size and we also always NUL-terminate strings.

Fixes: 2b2427d06426 ("phy: micrel: Add ethtool statistics counters")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/net/phy/micrel.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 0f45310300f6..49be85afbea9 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c

@@ -664,8 +664,8 @@ static void kszphy_get_strings(struct phy_device *phydev, u8 *data)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(kszphy_hw_stats); i++) {
-		memcpy(data + i * ETH_GSTRING_LEN,
-		       kszphy_hw_stats[i].string, ETH_GSTRING_LEN);
+		strlcpy(data + i * ETH_GSTRING_LEN,
+			kszphy_hw_stats[i].string, ETH_GSTRING_LEN);
 	}
 }
 

-- 
2.14.1

Our statistics strings are allocated at initialization without being
bound to a specific size, yet, we would copy ETH_GSTRING_LEN bytes using
memcpy() which would create out of bounds accesses, this was flagged by
KASAN. Replace this with strlcpy() to make sure we are bound the source
buffer size and we also always NUL-terminate strings.

Fixes: 820ee17b8d3b ("net: phy: broadcom: Add support code for reading PHY counters")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/net/phy/bcm-phy-lib.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/bcm-phy-lib.c b/drivers/net/phy/bcm-phy-lib.c
index 171010eb4d9c..5ad130c3da43 100644
--- a/drivers/net/phy/bcm-phy-lib.c
+++ b/drivers/net/phy/bcm-phy-lib.c

@@ -341,8 +341,8 @@ void bcm_phy_get_strings(struct phy_device *phydev, u8 *data)
 	unsigned int i;
 
 	for (i = 0; i < ARRAY_SIZE(bcm_phy_hw_stats); i++)
-		memcpy(data + i * ETH_GSTRING_LEN,
-		       bcm_phy_hw_stats[i].string, ETH_GSTRING_LEN);
+		strlcpy(data + i * ETH_GSTRING_LEN,
+			bcm_phy_hw_stats[i].string, ETH_GSTRING_LEN);
 }
 EXPORT_SYMBOL_GPL(bcm_phy_get_strings);
 

-- 
2.14.1

Our statistics strings are allocated at initialization without being
bound to a specific size, yet, we would copy ETH_GSTRING_LEN bytes using
memcpy() which would create out of bounds accesses, this was flagged by
KASAN. Replace this with strlcpy() to make sure we are bound the source
buffer size and we also always NUL-terminate strings.

Fixes: d2fa47d9dd5c ("phy: marvell: Add ethtool statistics counters")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/net/phy/marvell.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
index 22d9bc9c33a4..0e0978d8a0eb 100644
--- a/drivers/net/phy/marvell.c
+++ b/drivers/net/phy/marvell.c

@@ -1452,8 +1452,8 @@ static void marvell_get_strings(struct phy_device *phydev, u8 *data)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(marvell_hw_stats); i++) {
-		memcpy(data + i * ETH_GSTRING_LEN,
-		       marvell_hw_stats[i].string, ETH_GSTRING_LEN);
+		strlcpy(data + i * ETH_GSTRING_LEN,
+			marvell_hw_stats[i].string, ETH_GSTRING_LEN);
 	}
 }
 

-- 
2.14.1

On Fri, Mar 02, 2018 at 03:08:35PM -0800, Florian Fainelli wrote:

Hi all,

After turning on KASAN on one of my systems, I started getting lots of out of
bounds errors while fetching a given port's statistics, and indeed using
memcpy() is unsafe for copying strings which have not been declared as an array
of ETH_GSTRING_LEN bytes, so let's use strlcpy() instead. This allows the best
of both worlds: we still keep the efficient memory usage of variably sized
strings, but we don't copy more than we need to.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

From: Florian Fainelli <f.fainelli@gmail.com>
Date: Fri,  2 Mar 2018 15:08:35 -0800

After turning on KASAN on one of my systems, I started getting lots of out of
bounds errors while fetching a given port's statistics, and indeed using
memcpy() is unsafe for copying strings which have not been declared as an array
of ETH_GSTRING_LEN bytes, so let's use strlcpy() instead. This allows the best
of both worlds: we still keep the efficient memory usage of variably sized
strings, but we don't copy more than we need to.

Changes in v2:
- dropped the 3 other patches that were not necessary
- use strlcpy() instead of strncpy()

Series applied, thanks Florian.