[PATCH v2 7/7] cifs: Validate content of WSL reparse point buffers

["Pali Rohár" <pali@kernel.org>]

WSL socket, fifo, char and block devices have empty reparse buffer.
Validate the length of the reparse buffer.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 fs/smb/client/reparse.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
index b9a50eb03522..3de91331c96c 100644
--- a/fs/smb/client/reparse.c
+++ b/fs/smb/client/reparse.c
@@ -1083,6 +1083,11 @@ int parse_reparse_point(struct reparse_data_buffer *buf,
 	case IO_REPARSE_TAG_LX_FIFO:
 	case IO_REPARSE_TAG_LX_CHR:
 	case IO_REPARSE_TAG_LX_BLK:
+		if (le16_to_cpu(buf->ReparseDataLength) != 0) {
+			cifs_dbg(VFS, "srv returned malformed buffer for reparse point: 0x%08x\n",
+				 le32_to_cpu(buf->ReparseTag));
+			return -EIO;
+		}
 		break;
 	default:
 		cifs_tcon_dbg(VFS | ONCE, "unhandled reparse tag: 0x%08x\n",
-- 
2.20.1