[PATCH 6.18.y 5/7] smb/server: fix minimum SMB1 PDU size

[Sasha Levin <sashal@kernel.org>]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

[ Upstream commit 3b9c30eb8f5aaad4a54cdfa470b74c0467cc71e8 ]

Since the RFC1002 header has been removed from `struct smb_hdr`,
the minimum SMB1 PDU size should be updated as well.

Fixes: 83bfbd0bb902 ("cifs: Remove the RFC1002 header from smb_hdr")
Suggested-by: David Howells <dhowells@redhat.com>
Suggested-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Stable-dep-of: cfc0b8e5080a ("ksmbd: validate minimum PDU size for transform requests")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/smb/server/connection.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c
index edab0edaf18c3..0c583a7aaf1e2 100644
--- a/fs/smb/server/connection.c
+++ b/fs/smb/server/connection.c
@@ -376,7 +376,8 @@ bool ksmbd_conn_alive(struct ksmbd_conn *conn)
 	return true;
 }
 
-#define SMB1_MIN_SUPPORTED_HEADER_SIZE (sizeof(struct smb_hdr))
+/* "+2" for BCC field (ByteCount, 2 bytes) */
+#define SMB1_MIN_SUPPORTED_PDU_SIZE (sizeof(struct smb_hdr) + 2)
 #define SMB2_MIN_SUPPORTED_HEADER_SIZE (sizeof(struct smb2_hdr) + 4)
 
 /**
@@ -444,7 +445,7 @@ int ksmbd_conn_handler_loop(void *p)
 		if (pdu_size > MAX_STREAM_PROT_LEN)
 			break;
 
-		if (pdu_size < SMB1_MIN_SUPPORTED_HEADER_SIZE)
+		if (pdu_size < SMB1_MIN_SUPPORTED_PDU_SIZE)
 			break;
 
 		/* 4 for rfc1002 length field */
-- 
2.53.0