linux-kernel - [PATCH AUTOSEL 6.6 36/38] smb: client: increase number of PDUs allowed in a compound request

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Date: Wed,  7 Feb 2024 16:23:22 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Paulo Alcantara <pc@...guebit.com>,
	Steve French <stfrench@...rosoft.com>,
	Sasha Levin <sashal@...nel.org>,
	sfrench@...ba.org,
	linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org
Subject: [PATCH AUTOSEL 6.6 36/38] smb: client: increase number of PDUs allowed in a compound request

From: Paulo Alcantara <pc@...guebit.com>

[ Upstream commit 11d4d1dba3315f73d2d1d386f5bf4811a8241d45 ]

With the introduction of SMB2_OP_QUERY_WSL_EA, the client may now send
5 commands in a single compound request in order to query xattrs from
potential WSL reparse points, which should be fine as we currently
allow up to 5 PDUs in a single compound request.  However, if
encryption is enabled (e.g. 'seal' mount option) or enforced by the
server, current MAX_COMPOUND(5) won't be enough as we require an extra
PDU for the transform header.

Fix this by increasing MAX_COMPOUND to 7 and, while we're at it, add
an WARN_ON_ONCE() and return -EIO instead of -ENOMEM in case we
attempt to send a compound request that couldn't include the extra
transform header.

Signed-off-by: Paulo Alcantara <pc@...guebit.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/smb/client/cifsglob.h  | 2 +-
 fs/smb/client/transport.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 75ca732a1679..b65ce8d13143 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -82,7 +82,7 @@
 #define SMB_INTERFACE_POLL_INTERVAL	600
 
 /* maximum number of PDUs in one compound */
-#define MAX_COMPOUND 5
+#define MAX_COMPOUND 7
 
 /*
  * Default number of credits to keep available for SMB3.
diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
index 4f717ad7c21b..2d9146600371 100644
--- a/fs/smb/client/transport.c
+++ b/fs/smb/client/transport.c
@@ -428,8 +428,8 @@ smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 	if (!(flags & CIFS_TRANSFORM_REQ))
 		return __smb_send_rqst(server, num_rqst, rqst);
 
-	if (num_rqst > MAX_COMPOUND - 1)
-		return -ENOMEM;
+	if (WARN_ON_ONCE(num_rqst > MAX_COMPOUND - 1))
+		return -EIO;
 
 	if (!server->ops->init_transform_rq) {
 		cifs_server_dbg(VFS, "Encryption requested but transform callback is missing\n");
-- 
2.43.0