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net: dsa: mv88e6xxx: hwtstamp: fix potential negative array index read

PATCH In review Gustavo A. R. Silva 3 participants 6 messages Feb 15, 2018 – Feb 16, 2018

Subsystems (4)
Networking Network drivers Networking DSA Marvell 88E6XXX Ethernet switch fabric driver
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Gustavo A. R. Silva

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#0 lore raw

PATCH v2 1/1 net: dsa: mv88e6xxx: hwtstamp: fix potential negative array index read

_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 <[email protected]>

---
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(-)
drivers/net/dsa/mv88e6xxx/hwtstamp.c +7 -3
index b251d53..5a665aa 100644
@@ -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;
Signature · 1 line
2.7.4
maintainer Reviewed-by on v2 1/1
#1 lore raw
Quoted 5 lines · Gustavo A. R. Silva

_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))

Quoted 7 lines

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 <[email protected]>
Reviewed-by Andrew Lunn <[email protected]>

Andrew

#2 lore raw
In reply to Gustavo A. R. Silva
Quoted 7 lines · Gustavo A. R. Silva

_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.

NAK. Port is already known to be valid in the callers.

See:

*** net/dsa/slave.c:  dsa_slave_ioctl[266]
*** net/dsa/slave.c:  dsa_skb_tx_timestamp[416]
*** net/dsa/dsa.c:    dsa_skb_defer_rx_timestamp[152]
Quoted 2 lines

Addresses-Coverity-ID: 1465287 ("Negative array index read")
Addresses-Coverity-ID: 1465291 ("Negative array index read")

Please check the code before posting. These false positives are really annoying.

Thanks,
Richard

maintainer
#3 lore raw
Quoted 10 lines · Richard Cochran
Quoted 7 lines · Gustavo A. R. Silva

_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.

NAK. Port is already known to be valid in the callers.

Then we should take out the check. It is probably this check which is causing the false positives.

Andrew

#4 lore raw
In reply to Richard Cochran
Quoted 10 lines · Richard Cochran
Quoted 7 lines · Gustavo A. R. Silva

_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.

NAK. Port is already known to be valid in the callers.

And so the real bug is the pointless range checking tests. I would welcome patches to remove those.

Thanks,
Richard

author
#5 lore raw
Quoted 7 lines · Richard Cochran
Quoted 6 lines · Richard Cochran
Quoted 5 lines · Gustavo A. R. Silva

_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))

Quoted 8 lines
Quoted 4 lines
Quoted 2 lines

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

NAK. Port is already known to be valid in the callers.

And so the real bug is the pointless range checking tests. I would welcome patches to remove those.

I just sent a patch for this.

Thank you both, Andrew and Richard for the feedback. --
Gustavo