From acf50ff9360ef9d69560d80c0ec93fd5565e6f20 Mon Sep 17 00:00:00 2001 From: Li Nan Date: Fri, 8 Dec 2023 14:56:47 +0800 Subject: [PATCH] ksmbd: validate the zero field of packet header [ Upstream commit 516b3eb8c8065f7465f87608d37a7ed08298c7a5 ] The SMB2 Protocol requires that "The first byte of the Direct TCP transport packet header MUST be zero (0x00)"[1]. Commit 1c1bcf2d3ea0 ("ksmbd: validate smb request protocol id") removed the validation of this 1-byte zero. Add the validation back now. [1]: [MS-SMB2] - v20230227, page 30. https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-SMB2/%5bMS-SMB2%5d-230227.pdf Fixes: 1c1bcf2d3ea0 ("ksmbd: validate smb request protocol id") Signed-off-by: Li Nan Acked-by: Tom Talpey Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/smb/server/smb_common.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/smb/server/smb_common.c b/fs/smb/server/smb_common.c index 6691ae6..7c98bf6 100644 --- a/fs/smb/server/smb_common.c +++ b/fs/smb/server/smb_common.c @@ -158,8 +158,12 @@ int ksmbd_verify_smb_message(struct ksmbd_work *work) */ bool ksmbd_smb_request(struct ksmbd_conn *conn) { - __le32 *proto = (__le32 *)smb2_get_msg(conn->request_buf); + __le32 *proto; + if (conn->request_buf[0] != 0) + return false; + + proto = (__le32 *)smb2_get_msg(conn->request_buf); if (*proto == SMB2_COMPRESSION_TRANSFORM_ID) { pr_err_ratelimited("smb2 compression not support yet"); return false; -- 2.7.4