Patch "hpfs: fix remount failure when there are no options changed" has been added to the 4.6-stable tree

Patch "hpfs: fix remount failure when there are no options changed" has been added to the 4.6-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    hpfs: fix remount failure when there are no options changed

to the 4.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hpfs-fix-remount-failure-when-there-are-no-options-changed.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 44d51706b4685f965cd32acde3fe0fcc1e6198e8 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mikulas@twibright.com>
Date: Tue, 24 May 2016 22:47:00 +0200
Subject: hpfs: fix remount failure when there are no options changed

From: Mikulas Patocka <mikulas@twibright.com>

commit 44d51706b4685f965cd32acde3fe0fcc1e6198e8 upstream.

Commit ce657611baf9 ("hpfs: kstrdup() out of memory handling") checks if
the kstrdup function returns NULL due to out-of-memory condition.

However, if we are remounting a filesystem with no change to
filesystem-specific options, the parameter data is NULL.  In this case,
kstrdup returns NULL (because it was passed NULL parameter), although no
out of memory condition exists.  The mount syscall then fails with
ENOMEM.

This patch fixes the bug.  We fail with ENOMEM only if data is non-NULL.

The patch also changes the call to replace_mount_options - if we didn't
pass any filesystem-specific options, we don't call
replace_mount_options (thus we don't erase existing reported options).

Fixes: ce657611baf9 ("hpfs: kstrdup() out of memory handling")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/hpfs/super.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/hpfs/super.c
+++ b/fs/hpfs/super.c
@@ -455,7 +455,7 @@ static int hpfs_remount_fs(struct super_
 	struct hpfs_sb_info *sbi = hpfs_sb(s);
 	char *new_opts = kstrdup(data, GFP_KERNEL);
 
-	if (!new_opts)
+	if (data && !new_opts)
 		return -ENOMEM;
 
 	sync_filesystem(s);
@@ -493,7 +493,8 @@ static int hpfs_remount_fs(struct super_
 
 	if (!(*flags & MS_RDONLY)) mark_dirty(s, 1);
 
-	replace_mount_options(s, new_opts);
+	if (new_opts)
+		replace_mount_options(s, new_opts);
 
 	hpfs_unlock(s);
 	return 0;


Patches currently in stable-queue which might be from mikulas@twibright.com are

queue-4.6/hpfs-fix-remount-failure-when-there-are-no-options-changed.patch
queue-4.6/hpfs-implement-the-show_options-method.patch