msm: ipa: fix potential heap overflow in intf property queries.

Number of TX/RX/EXT properties to be read is supplied by
user-space and if these values are maliciously set too large,
heap overflow and memory corruption can result. This commit
caps the max allowed interface properties.

Change-Id: I9f5bf8b5e9a1b3b47b0741c0b00d5fafc77b28e2
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>
Signed-off-by: Venkata Aravind <venkata@codeaurora.org>

drivers/platform/msm/ipa/ipa.c

@@ -544,6 +544,13 @@ static long ipa_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 			retval = -EFAULT;
 			break;
 		}
+
+		if (((struct ipa_ioc_query_intf_tx_props *)header)->num_tx_props
+				> IPA_NUM_PROPS_MAX) {
+			retval = -EFAULT;
+			break;
+		}
+
 		pyld_sz = sz + ((struct ipa_ioc_query_intf_tx_props *)
 				header)->num_tx_props *
 			sizeof(struct ipa_ioc_tx_intf_prop);
@@ -572,6 +579,13 @@ static long ipa_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 			retval = -EFAULT;
 			break;
 		}
+
+		if (((struct ipa_ioc_query_intf_rx_props *)header)->num_rx_props
+				> IPA_NUM_PROPS_MAX) {
+			retval = -EFAULT;
+			break;
+		}
+
 		pyld_sz = sz + ((struct ipa_ioc_query_intf_rx_props *)
 				header)->num_rx_props *
 			sizeof(struct ipa_ioc_rx_intf_prop);

drivers/platform/msm/ipa/ipa_intf.c

@@ -60,6 +60,18 @@ int ipa_register_intf(const char *name, const struct ipa_tx_intf *tx,
 		return -EINVAL;
 	}
 
+	if (tx && tx->num_props > IPA_NUM_PROPS_MAX) {
+		IPAERR("invalid tx num_props=%d max=%d\n", tx->num_props,
+				IPA_NUM_PROPS_MAX);
+		return -EINVAL;
+	}
+
+	if (rx && rx->num_props > IPA_NUM_PROPS_MAX) {
+		IPAERR("invalid rx num_props=%d max=%d\n", rx->num_props,
+				IPA_NUM_PROPS_MAX);
+		return -EINVAL;
+	}
+
 	len = sizeof(struct ipa_intf);
 	intf = kzalloc(len, GFP_KERNEL);
 	if (intf == NULL) {

include/linux/msm_ipa.h

@@ -63,6 +63,11 @@
  */
 #define IPA_RESOURCE_NAME_MAX 20
 
+/**
+ * max number of interface properties
+ */
+#define IPA_NUM_PROPS_MAX 20
+
 /**
  * size of the mac address
  */