releases/5.15.190/cifs-fix-calling-cifsfindfirst-for-root-path-without.patch

From 9fd8695a7dac8cbc5328d714b93085e6a3039112 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Mon, 30 Dec 2024 20:54:11 +0100
Subject: cifs: Fix calling CIFSFindFirst() for root path without msearch
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From: Pali Rohár <pali@kernel.org>

[ Upstream commit b460249b9a1dab7a9f58483e5349d045ad6d585c ]

To query root path (without msearch wildcard) it is needed to
send pattern '\' instead of '' (empty string).

This allows to use CIFSFindFirst() to query information about root path
which is being used in followup changes.

This change fixes the stat() syscall called on the root path on the mount.
It is because stat() syscall uses the cifs_query_path_info() function and
it can fallback to the CIFSFindFirst() usage with msearch=false.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/cifssmb.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 6ca08e473a7e..e6541bd5c63d 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -4362,6 +4362,12 @@ CIFSFindFirst(const unsigned int xid, struct cifs_tcon *tcon,
 			pSMB->FileName[name_len] = 0;
 			pSMB->FileName[name_len+1] = 0;
 			name_len += 2;
+		} else if (!searchName[0]) {
+			pSMB->FileName[0] = CIFS_DIR_SEP(cifs_sb);
+			pSMB->FileName[1] = 0;
+			pSMB->FileName[2] = 0;
+			pSMB->FileName[3] = 0;
+			name_len = 4;
 		}
 	} else {
 		name_len = copy_path_name(pSMB->FileName, searchName);
@@ -4373,6 +4379,10 @@ CIFSFindFirst(const unsigned int xid, struct cifs_tcon *tcon,
 			pSMB->FileName[name_len] = '*';
 			pSMB->FileName[name_len+1] = 0;
 			name_len += 2;
+		} else if (!searchName[0]) {
+			pSMB->FileName[0] = CIFS_DIR_SEP(cifs_sb);
+			pSMB->FileName[1] = 0;
+			name_len = 2;
 		}
 	}
 
-- 
2.39.5