[PATCH 5.10.y] smb: client: clean up failed cached directory opens

[Sasha Levin <sashal@kernel.org>]

From: Zihan Xi <zihanx@nebusec.ai>

[ Upstream commit d2ff5fb93ea83034025850266b5eed391f96b825 ]

open_cached_dir() sends CREATE and QUERY_INFO as a compound request. If
the CREATE succeeds but a later command returns an error, the function
must retain the CREATE FID so common cleanup can issue SMB2_close(). It
also must not treat a response error as a valid CREATE.

Validate the CREATE response before using its fields, record the FIDs, and
mark the handle open before handling errors from later compound commands.
Move the -EREMCHG reconnect handling before response validation so a
missing response does not hide the reconnect request. Count the handle
when it is marked open; confirmed close responses decrement the counter,
while existing close retry behavior remains best effort on transport
failures.

Fixes: b0f6df737a1c ("cifs: cache FILE_ALL_INFO for the shared root handle")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Assisted-by: LLM
Co-developed-by: Luxing Yin <root@tr0jan.top>
Signed-off-by: Luxing Yin <root@tr0jan.top>
Signed-off-by: Zihan Xi <zihanx@nebusec.ai>
Tested-by: Frank Sorenson <sorenson@redhat.com>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
[ adapted open_cached_dir() changes to the older open_shroot() implementation. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/smb2ops.c | 43 +++++++++++++++++++++++++++++--------------
 1 file changed, 29 insertions(+), 14 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 51f8ea0c89065..94a604dd2866b 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -766,6 +766,33 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
 	rc = compound_send_recv(xid, ses, server,
 				flags, 2, rqst,
 				resp_buftype, rsp_iov);
+	if (rc == -EREMCHG) {
+		tcon->need_reconnect = true;
+		pr_warn_once("server share %s deleted\n",
+			     tcon->treeName);
+	}
+
+	if (!rsp_iov[0].iov_base || rsp_iov[0].iov_len < sizeof(*o_rsp)) {
+		if (!rc)
+			rc = -EIO;
+		goto oshr_free;
+	}
+
+	o_rsp = (struct smb2_create_rsp *)rsp_iov[0].iov_base;
+	if (o_rsp->hdr.Status != STATUS_SUCCESS) {
+		if (!rc)
+			rc = -EIO;
+		goto oshr_free;
+	}
+
+	atomic_inc(&tcon->num_remote_opens);
+
+	if (rc) {
+		SMB2_close(xid, tcon, o_rsp->PersistentFileId,
+			   o_rsp->VolatileFileId);
+		goto oshr_free;
+	}
+
 	mutex_lock(&tcon->crfid.fid_mutex);
 
 	/*
@@ -778,8 +805,8 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
 
 		/* stash fids for close() later */
 		struct cifs_fid fid = {
-			.persistent_fid = pfid->persistent_fid,
-			.volatile_fid = pfid->volatile_fid,
+			.persistent_fid = o_rsp->PersistentFileId,
+			.volatile_fid = o_rsp->VolatileFileId,
 		};
 
 		/*
@@ -802,18 +829,6 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
 
 	/* Cached root is still invalid, continue normaly */
 
-	if (rc) {
-		if (rc == -EREMCHG) {
-			tcon->need_reconnect = true;
-			pr_warn_once("server share %s deleted\n",
-				     tcon->treeName);
-		}
-		goto oshr_exit;
-	}
-
-	atomic_inc(&tcon->num_remote_opens);
-
-	o_rsp = (struct smb2_create_rsp *)rsp_iov[0].iov_base;
 	oparms.fid->persistent_fid = o_rsp->PersistentFileId;
 	oparms.fid->volatile_fid = o_rsp->VolatileFileId;
 #ifdef CONFIG_CIFS_DEBUG2
-- 
2.53.0