From 97bba24c9f80a7181bfc58bbf819209fb8b21128 Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc@cjr.nz>
Date: Mon, 8 Aug 2022 13:41:18 -0300
Subject: [PATCH] cifs: fix lock length calculation

The lock length was wrongly set to 0 when fl_end == OFFSET_MAX, thus
failing to lock the whole file when l_start=0 and l_len=0.

This fixes test 2 from cthon04.

Before patch:

$ ./cthon04/lock/tlocklfs -t 2 /mnt

Creating parent/child synchronization pipes.

Test #1 - Test regions of an unlocked file.
        Parent: 1.1  - F_TEST  [               0,               1] PASSED.
        Parent: 1.2  - F_TEST  [               0,          ENDING] PASSED.
        Parent: 1.3  - F_TEST  [               0,7fffffffffffffff] PASSED.
        Parent: 1.4  - F_TEST  [               1,               1] PASSED.
        Parent: 1.5  - F_TEST  [               1,          ENDING] PASSED.
        Parent: 1.6  - F_TEST  [               1,7fffffffffffffff] PASSED.
        Parent: 1.7  - F_TEST  [7fffffffffffffff,               1] PASSED.
        Parent: 1.8  - F_TEST  [7fffffffffffffff,          ENDING] PASSED.
        Parent: 1.9  - F_TEST  [7fffffffffffffff,7fffffffffffffff] PASSED.

Test #2 - Try to lock the whole file.
        Parent: 2.0  - F_TLOCK [               0,          ENDING] PASSED.
        Child:  2.1  - F_TEST  [               0,               1] FAILED!
        Child:  **** Expected EACCES, returned success...
        Child:  **** Probably implementation error.

**  CHILD pass 1 results: 0/0 pass, 0/0 warn, 1/1 fail (pass/total).
        Parent: Child died

** PARENT pass 1 results: 10/10 pass, 0/0 warn, 0/0 fail (pass/total).

After patch:

$ ./cthon04/lock/tlocklfs -t 2 /mnt

Creating parent/child synchronization pipes.

Test #2 - Try to lock the whole file.
        Parent: 2.0  - F_TLOCK [               0,          ENDING] PASSED.
        Child:  2.1  - F_TEST  [               0,               1] PASSED.
        Child:  2.2  - F_TEST  [               0,          ENDING] PASSED.
        Child:  2.3  - F_TEST  [               0,7fffffffffffffff] PASSED.
        Child:  2.4  - F_TEST  [               1,               1] PASSED.
        Child:  2.5  - F_TEST  [               1,          ENDING] PASSED.
        Child:  2.6  - F_TEST  [               1,7fffffffffffffff] PASSED.
        Child:  2.7  - F_TEST  [7fffffffffffffff,               1] PASSED.
        Child:  2.8  - F_TEST  [7fffffffffffffff,          ENDING] PASSED.
        Child:  2.9  - F_TEST  [7fffffffffffffff,7fffffffffffffff] PASSED.
        Parent: 2.10 - F_ULOCK [               0,          ENDING] PASSED.

** PARENT pass 1 results: 2/2 pass, 0/0 warn, 0/0 fail (pass/total).

**  CHILD pass 1 results: 9/9 pass, 0/0 warn, 0/0 fail (pass/total).

Fixes: d80c69846ddf ("cifs: fix signed integer overflow when fl_end is OFFSET_MAX")
Reported-by: Xiaoli Feng <xifeng@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifsglob.h | 4 ++--
 fs/cifs/file.c     | 5 ++---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 3070407cafa7..45a7a4a92643 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -2132,9 +2132,9 @@ static inline bool cifs_is_referral_server(struct cifs_tcon *tcon,
 	return is_tcon_dfs(tcon) || (ref && (ref->flags & DFSREF_REFERRAL_SERVER));
 }
 
-static inline u64 cifs_flock_len(struct file_lock *fl)
+static inline u64 cifs_flock_len(const struct file_lock *fl)
 {
-	return fl->fl_end == OFFSET_MAX ? 0 : fl->fl_end - fl->fl_start + 1;
+	return fl->fl_end - fl->fl_start + 1;
 }
 
 static inline size_t ntlmssp_workstation_name_size(const struct cifs_ses *ses)
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 85f2abcb2795..4ba019c260aa 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1936,9 +1936,8 @@ int cifs_lock(struct file *file, int cmd, struct file_lock *flock)
 	rc = -EACCES;
 	xid = get_xid();
 
-	cifs_dbg(FYI, "Lock parm: 0x%x flockflags: 0x%x flocktype: 0x%x start: %lld end: %lld\n",
-		 cmd, flock->fl_flags, flock->fl_type,
-		 flock->fl_start, flock->fl_end);
+	cifs_dbg(FYI, "%s: %pD2 cmd=0x%x type=0x%x flags=0x%x r=%Ld:%Ld\n", __func__, file, cmd,
+		 flock->fl_flags, flock->fl_type, flock->fl_start, flock->fl_end);
 
 	cfile = (struct cifsFileInfo *)file->private_data;
 	tcon = tlink_tcon(cfile->tlink);
-- 
2.34.1

