[PATCH 5.15.y] ksmbd: initialize FileSystemControlFlags in FS_CONTROL_INFORMATION

[Sasha Levin <sashal@kernel.org>]

From: Aleksandr Khromov <haa@amicon.ru>

[ Upstream commit c0cd3fc6824122014da2b3b0cb7ddeaa2946ec8e ]

smb2_get_info_filesystem() reports 48 bytes for FS_CONTROL_INFORMATION,
that is the whole of struct smb2_fs_control_info, but never assigns
FileSystemControlFlags.  Those four bytes go to the client as they are
found in the response buffer.

The buffer is zeroed on allocation, so a standalone request leaks
nothing.  A compound request can leak: the offset of the next response
is advanced by the length pinned for the previous one, so a reply that
was written into the buffer and then dropped in favour of the short
error response of smb2_set_err_rsp() stays there, and the next reply is
laid over it with only the header cleared.

ksmbd does not implement quota tracking, so report no control flags.

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Signed-off-by: Aleksandr Khromov <haa@amicon.ru>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ksmbd/smb2pdu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index de03750a2b0c9..6e3acd0a5687a 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -5247,6 +5247,7 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
 		info->FreeSpaceStopFiltering = 0;
 		info->DefaultQuotaThreshold = cpu_to_le64(SMB2_NO_FID);
 		info->DefaultQuotaLimit = cpu_to_le64(SMB2_NO_FID);
+		info->FileSystemControlFlags = 0;
 		info->Padding = 0;
 		rsp->OutputBufferLength = cpu_to_le32(48);
 		break;
-- 
2.53.0