[PATCH v2] net: dsa: mv88e6xxx: hwtstamp: fix potential negative array index read

Gustavo A. R. Silva
2018-02-15T18:31:48Z

_port_ is being used as index to array port_hwtstamp before verifying
it is a non-negative number and a valid index at line 209 and 258:

if (port < 0 || port >= mv88e6xxx_num_ports(chip))

Fix this by checking _port_ before using it as index to array
port_hwtstamp.

Addresses-Coverity-ID: 1465287 ("Negative array index read")
Addresses-Coverity-ID: 1465291 ("Negative array index read")
Fixes: c6fe0ad2c349 ("net: dsa: mv88e6xxx: add rx/tx timestamping support")
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
Changes in v2:
-Fix the same issue in mv88e6xxx_should_tstamp.
-Update commit message.

drivers/net/dsa/mv88e6xxx/hwtstamp.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/hwtstamp.c b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
index b251d53..5a665aa 100644
--- a/drivers/net/dsa/mv88e6xxx/hwtstamp.c
+++ b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
@@ -200,8 +200,8 @@ int mv88e6xxx_port_hwtstamp_get(struct dsa_switch *ds, int port,
struct ifreq *ifr)
{
struct mv88e6xxx_chip *chip = ds->priv;
- struct mv88e6xxx_port_hwtstamp *ps = &chip->port_hwtstamp[port];
- struct hwtstamp_config *config = &ps->tstamp_config;
+ struct mv88e6xxx_port_hwtstamp *ps;
+ struct hwtstamp_config *config;

if (!chip->info->ptp_support)
return -EOPNOTSUPP;
@@ -209,6 +209,9 @@ int mv88e6xxx_port_hwtstamp_get(struct dsa_switch *ds, int port,
if (port < 0 || port >= mv88e6xxx_num_ports(chip))
return -EINVAL;

+ ps = &chip->port_hwtstamp[port];
+ config = &ps->tstamp_config;
+
return copy_to_user(ifr->ifr_data, config, sizeof(*config)) ?
-EFAULT : 0;
}
@@ -249,7 +252,7 @@ static u8 *parse_ptp_header(struct sk_buff *skb, unsigned int type)
static u8 *mv88e6xxx_should_tstamp(struct mv88e6xxx_chip *chip, int port,
struct sk_buff *skb, unsigned int type)
{
- struct mv88e6xxx_port_hwtstamp *ps = &chip->port_hwtstamp[port];
+ struct mv88e6xxx_port_hwtstamp *ps;
u8 *hdr;

if (!chip->info->ptp_support)
@@ -262,6 +265,7 @@ static u8 *mv88e6xxx_should_tstamp(struct mv88e6xxx_chip *chip, int port,
if (!hdr)
return NULL;

+ ps = &chip->port_hwtstamp[port];
if (!test_bit(MV88E6XXX_HWTSTAMP_ENABLED, &ps->state))
return NULL;

--
2.7.4