[PATCH] net: cxgb3_main: fix a missing-check bug

[PATCH] net: cxgb3_main: fix a missing-check bug

[Wenwen Wang]

In cxgb_extension_ioctl(), the command of the ioctl is firstly copied from
the user-space buffer 'useraddr' to 'cmd' and checked through the
switch statement. If the command is not as expected, an error code
EOPNOTSUPP is returned. In the following execution, i.e., the cases of the
switch statement, the whole buffer of 'useraddr' is copied again to a
specific data structure, according to what kind of command is requested.
However, after the second copy, there is no re-check on the newly-copied
command. Given that the buffer 'useraddr' is in the user space, a malicious
user can race to change the command between the two copies. By doing so,
the attacker can supply malicious data to the kernel and cause undefined
behavior.

This patch adds a re-check in each case of the switch statement if there is
a second copy in that case, to re-check whether the command obtained in the
second copy is the same as the one in the first copy. If not, an error code
EINVAL is returned.

Signed-off-by: Wenwen Wang <wang6495@umn.edu>
---
 drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c b/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c
index a19172d..c34ea38 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c
@@ -2159,6 +2159,8 @@ static int cxgb_extension_ioctl(struct net_device *dev, void __user *useraddr)
 			return -EPERM;
 		if (copy_from_user(&t, useraddr, sizeof(t)))
 			return -EFAULT;
+		if (t.cmd != CHELSIO_SET_QSET_PARAMS)
+			return -EINVAL;
 		if (t.qset_idx >= SGE_QSETS)
 			return -EINVAL;
 		if (!in_range(t.intr_lat, 0, M_NEWTIMER) ||
@@ -2258,6 +2260,9 @@ static int cxgb_extension_ioctl(struct net_device *dev, void __user *useraddr)
 		if (copy_from_user(&t, useraddr, sizeof(t)))
 			return -EFAULT;
 
+		if (t.cmd != CHELSIO_GET_QSET_PARAMS)
+			return -EINVAL;
+
 		/* Display qsets for all ports when offload enabled */
 		if (test_bit(OFFLOAD_DEVMAP_BIT, &adapter->open_device_map)) {
 			q1 = 0;
@@ -2303,6 +2308,8 @@ static int cxgb_extension_ioctl(struct net_device *dev, void __user *useraddr)
 			return -EBUSY;
 		if (copy_from_user(&edata, useraddr, sizeof(edata)))
 			return -EFAULT;
+		if (edata.cmd != CHELSIO_SET_QSET_NUM)
+			return -EINVAL;
 		if (edata.val < 1 ||
 			(edata.val > 1 && !(adapter->flags & USING_MSIX)))
 			return -EINVAL;
@@ -2343,6 +2350,8 @@ static int cxgb_extension_ioctl(struct net_device *dev, void __user *useraddr)
 			return -EPERM;
 		if (copy_from_user(&t, useraddr, sizeof(t)))
 			return -EFAULT;
+		if (t.cmd != CHELSIO_LOAD_FW)
+			return -EINVAL;
 		/* Check t.len sanity ? */
 		fw_data = memdup_user(useraddr + sizeof(t), t.len);
 		if (IS_ERR(fw_data))
@@ -2366,6 +2375,8 @@ static int cxgb_extension_ioctl(struct net_device *dev, void __user *useraddr)
 			return -EBUSY;
 		if (copy_from_user(&m, useraddr, sizeof(m)))
 			return -EFAULT;
+		if (m.cmd != CHELSIO_SETMTUTAB)
+			return -EINVAL;
 		if (m.nmtus != NMTUS)
 			return -EINVAL;
 		if (m.mtus[0] < 81)	/* accommodate SACK */
@@ -2407,6 +2418,8 @@ static int cxgb_extension_ioctl(struct net_device *dev, void __user *useraddr)
 			return -EBUSY;
 		if (copy_from_user(&m, useraddr, sizeof(m)))
 			return -EFAULT;
+		if (m.cmd != CHELSIO_SET_PM)
+			return -EINVAL;
 		if (!is_power_of_2(m.rx_pg_sz) ||
 			!is_power_of_2(m.tx_pg_sz))
 			return -EINVAL;	/* not power of 2 */
@@ -2440,6 +2453,8 @@ static int cxgb_extension_ioctl(struct net_device *dev, void __user *useraddr)
 			return -EIO;	/* need the memory controllers */
 		if (copy_from_user(&t, useraddr, sizeof(t)))
 			return -EFAULT;
+		if (t.cmd != CHELSIO_GET_MEM)
+			return -EINVAL;
 		if ((t.addr & 7) || (t.len & 7))
 			return -EINVAL;
 		if (t.mem_id == MEM_CM)
@@ -2492,6 +2507,8 @@ static int cxgb_extension_ioctl(struct net_device *dev, void __user *useraddr)
 			return -EAGAIN;
 		if (copy_from_user(&t, useraddr, sizeof(t)))
 			return -EFAULT;
+		if (t.cmd != CHELSIO_SET_TRACE_FILTER)
+			return -EINVAL;
 
 		tp = (const struct trace_params *)&t.sip;
 		if (t.config_tx)
-- 
2.7.4

Re: [PATCH] net: cxgb3_main: fix a missing-check bug

[David Miller]

From: Wenwen Wang <wang6495@umn.edu>
Date: Fri,  5 Oct 2018 08:48:27 -0500

> In cxgb_extension_ioctl(), the command of the ioctl is firstly copied from
> the user-space buffer 'useraddr' to 'cmd' and checked through the
> switch statement. If the command is not as expected, an error code
> EOPNOTSUPP is returned. In the following execution, i.e., the cases of the
> switch statement, the whole buffer of 'useraddr' is copied again to a
> specific data structure, according to what kind of command is requested.
> However, after the second copy, there is no re-check on the newly-copied
> command. Given that the buffer 'useraddr' is in the user space, a malicious
> user can race to change the command between the two copies. By doing so,
> the attacker can supply malicious data to the kernel and cause undefined
> behavior.
> 
> This patch adds a re-check in each case of the switch statement if there is
> a second copy in that case, to re-check whether the command obtained in the
> second copy is the same as the one in the first copy. If not, an error code
> EINVAL is returned.
> 
> Signed-off-by: Wenwen Wang <wang6495@umn.edu>

Applied.