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net/mlx5: prevent an integer underflow in mlx5_perout_configure()

PATCH In review Dan Carpenter 3 participants 4 messages Feb 19, 2021 – Mar 1, 2021

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Networking Network drivers Kernel janitors InfiniBand +1 more subsystems
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Dan Carpenter

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#0 lore raw

PATCH 1/1 net/mlx5: prevent an integer underflow in mlx5_perout_configure()

The value of "sec" comes from the user. Negative values will lead to shift wrapping inside the perout_conf_real_time() function and triggger a UBSan warning.

Add a check and return -EINVAL to prevent that from happening.

Fixes 432119de33d9 ("net/mlx5: Add cyc2time HW translation mode support")
Signed-off-by Dan Carpenter <[email protected]>

---
Saeed, I think this goes through your git tree and you will send a pull request to the networking?

From static analysis. Not tested.

 drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +1 -1
index b0e129d0f6d8..286824ca62b5 100644
@@ -516,7 +516,7 @@ static int mlx5_perout_configure(struct ptp_clock_info *ptp,
 		nsec = rq->perout.start.nsec;
 		sec = rq->perout.start.sec;
 
-		if (rt_mode && sec > U32_MAX)
+		if (rt_mode && (sec < 0 || sec > U32_MAX))
 			return -EINVAL;
 
 		time_stamp = rt_mode ? perout_conf_real_time(sec, nsec) :
Signature · 1 line
2.30.0
Reviewed-by on v1 1/1
#1 lore raw
Quoted 8 lines · Dan Carpenter

The value of "sec" comes from the user. Negative values will lead to shift wrapping inside the perout_conf_real_time() function and triggger a UBSan warning.

Add a check and return -EINVAL to prevent that from happening.

Fixes 432119de33d9 ("net/mlx5: Add cyc2time HW translation mode support")
Signed-off-by Dan Carpenter <[email protected]>
Quoted 9 lines

---
Saeed, I think this goes through your git tree and you will send a pull request to the networking?

From static analysis. Not tested.

 drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Thanks,

Reviewed-by Leon Romanovsky <[email protected]>
#2 lore raw
In reply to Dan Carpenter
Quoted 22 lines · Dan Carpenter

The value of "sec" comes from the user. Negative values will lead to shift wrapping inside the perout_conf_real_time() function and triggger a UBSan warning.

Add a check and return -EINVAL to prevent that from happening.

Fixes 432119de33d9 ("net/mlx5: Add cyc2time HW translation mode support")
Signed-off-by Dan Carpenter <[email protected]>

---
Saeed, I think this goes through your git tree and you will send a pull request to the networking?

From static analysis. Not tested.

  drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)
drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +0 -0
index b0e129d0f6d8..286824ca62b5 100644

drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c static int mlx5_perout_configure(struct ptp_clock_info *ptp, · line 519

Quoted 4 lines
drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +0 -1
@@ -516,7 +516,7 @@ static int mlx5_perout_configure(struct ptp_clock_info *ptp,
  		nsec = rq->perout.start.nsec;
  		sec = rq->perout.start.sec;
 
-		if (rt_mode && sec > U32_MAX)

This if clause was set to reject perout time start sec bigger than U32_MAX, as rt mode specifically doesn't support it.

A user negative values protection should be generic for all netdev drivers, inside the caller ioctl func, and not part of any driver code.

Quoted 5 lines
drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +1 -0
+		if (rt_mode && (sec < 0 || sec > U32_MAX))
  			return -EINVAL;
 
  		time_stamp = rt_mode ? perout_conf_real_time(sec, nsec) :
author
#3 lore raw
Quoted 32 lines · Eran Ben Elisha
Quoted 22 lines · Dan Carpenter

The value of "sec" comes from the user. Negative values will lead to shift wrapping inside the perout_conf_real_time() function and triggger a UBSan warning.

Add a check and return -EINVAL to prevent that from happening.

Fixes 432119de33d9 ("net/mlx5: Add cyc2time HW translation mode support")
Signed-off-by Dan Carpenter <[email protected]>

---
Saeed, I think this goes through your git tree and you will send a pull request to the networking?

From static analysis. Not tested.

  drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)
drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +0 -0
index b0e129d0f6d8..286824ca62b5 100644

drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c static int mlx5_perout_configure(struct ptp_clock_info *ptp, · line 518

Quoted 3 lines
drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +0 -1
@@ -516,7 +516,7 @@ static int mlx5_perout_configure(struct ptp_clock_info *ptp,
  		nsec = rq->perout.start.nsec;
  		sec = rq->perout.start.sec;
-		if (rt_mode && sec > U32_MAX)

This if clause was set to reject perout time start sec bigger than U32_MAX, as rt mode specifically doesn't support it.

Quoted 3 lines

A user negative values protection should be generic for all netdev drivers, inside the caller ioctl func, and not part of any driver code.

I'm not a networking expert... :/ It's easier for me to see that this code will trigger a syzbot splat vs saying that there is no valid use case for negative seconds any driver.

What you're saying sounds reasonable enough to me, but I don't know enough about networking to comment one way or the other. Maybe the other drivers have a use for negative seconds?

regards,
dan carpenter

Quoted 4 lines
Quoted 4 lines
drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +1 -0
+		if (rt_mode && (sec < 0 || sec > U32_MAX))
  			return -EINVAL;
  		time_stamp = rt_mode ? perout_conf_real_time(sec, nsec) :