From: Wenwen Wang <wang6495@umn.edu>
Date: Fri, 5 Oct 2018 08:48:27 -0500
Subject: net: cxgb3_main: fix a missing-check bug
Patch-mainline: v4.19-rc7
Git-commit: 2c05d88818ab6571816b93edce4d53703870d7ae
References: bsc#1109837

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

--- a/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c
@@ -2155,6 +2155,8 @@ static int cxgb_extension_ioctl(struct n
 			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) ||
@@ -2254,6 +2256,9 @@ static int cxgb_extension_ioctl(struct n
 		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;
@@ -2299,6 +2304,8 @@ static int cxgb_extension_ioctl(struct n
 			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;
@@ -2339,6 +2346,8 @@ static int cxgb_extension_ioctl(struct n
 			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))
@@ -2362,6 +2371,8 @@ static int cxgb_extension_ioctl(struct n
 			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 */
@@ -2403,6 +2414,8 @@ static int cxgb_extension_ioctl(struct n
 			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 */
@@ -2436,6 +2449,8 @@ static int cxgb_extension_ioctl(struct n
 			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)
@@ -2488,6 +2503,8 @@ static int cxgb_extension_ioctl(struct n
 			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)