[CIFS] Fix potential NULL pointer usage if kzalloc fails

Potential problem was noticed by Cyrill Gorcunov

CC: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifs_debug.c

@@ -209,13 +209,15 @@ cifs_debug_data_read(char *buf, char **beginBuffer, off_t offset,
 		i++;
 		tcon = list_entry(tmp, struct cifsTconInfo, cifsConnectionList);
 		dev_type = le32_to_cpu(tcon->fsDevInfo.DeviceType);
-		length =
-		    sprintf(buf,
-			    "\n%d) %s Uses: %d Type: %s DevInfo: 0x%x "
-			    "Attributes: 0x%x\nPathComponentMax: %d Status: %d",
-			    i, tcon->treeName,
-			    atomic_read(&tcon->useCount),
-			    tcon->nativeFileSystem,
+		length = sprintf(buf, "\n%d) %s Uses: %d ", i,
+				 tcon->treeName, atomic_read(&tcon->useCount));
+		buf += length;
+		if (tcon->nativeFileSystem) {
+			length = sprintf("Type: %s ", tcon->nativeFileSystem);
+			buf += length;
+		}
+		length = sprintf(buf, "DevInfo: 0x%x Attributes: 0x%x"
+				 "\nPathComponentMax: %d Status: %d",
 			    le32_to_cpu(tcon->fsDevInfo.DeviceCharacteristics),
 			    le32_to_cpu(tcon->fsAttrInfo.Attributes),
 			    le32_to_cpu(tcon->fsAttrInfo.MaxPathNameComponentLength),

fs/cifs/connect.c

@@ -3386,9 +3386,11 @@ CIFSTCon(unsigned int xid, struct cifsSesInfo *ses,
 				kfree(tcon->nativeFileSystem);
 				tcon->nativeFileSystem =
 				    kzalloc(length + 2, GFP_KERNEL);
-				cifs_strfromUCS_le(tcon->nativeFileSystem,
-						   (__le16 *) bcc_ptr,
-						   length, nls_codepage);
+				if (tcon->nativeFileSystem)
+					cifs_strfromUCS_le(
+						tcon->nativeFileSystem,
+						(__le16 *) bcc_ptr,
+						length, nls_codepage);
 				bcc_ptr += 2 * length;
 				bcc_ptr[0] = 0;	/* null terminate the string */
 				bcc_ptr[1] = 0;
@@ -3403,8 +3405,9 @@ CIFSTCon(unsigned int xid, struct cifsSesInfo *ses,
 				kfree(tcon->nativeFileSystem);
 				tcon->nativeFileSystem =
 				    kzalloc(length + 1, GFP_KERNEL);
-				strncpy(tcon->nativeFileSystem, bcc_ptr,
-					length);
+				if (tcon->nativeFileSystem)
+					strncpy(tcon->nativeFileSystem, bcc_ptr,
+						length);
 			}
 			/* else do not bother copying these information fields*/
 		}