Patch "isofs: Do not return EACCES for unknown filesystems" has been added to the 4.4-stable tree

Patch "isofs: Do not return EACCES for unknown filesystems" has been added to the 4.4-stable tree

[gregkh]

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

    isofs: Do not return EACCES for unknown filesystems

to the 4.4-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:
     isofs-do-not-return-eacces-for-unknown-filesystems.patch
and it can be found in the queue-4.4 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 a2ed0b391dd9c3ef1d64c7c3e370f4a5ffcd324a Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 4 Oct 2016 13:44:06 +0200
Subject: isofs: Do not return EACCES for unknown filesystems

From: Jan Kara <jack@suse.cz>

commit a2ed0b391dd9c3ef1d64c7c3e370f4a5ffcd324a upstream.

When isofs_mount() is called to mount a device read-write, it returns
EACCES even before it checks that the device actually contains an isofs
filesystem. This may confuse mount(8) which then tries to mount all
subsequent filesystem types in read-only mode.

Fix the problem by returning EACCES only once we verify that the device
indeed contains an iso9660 filesystem.

Fixes: 17b7f7cf58926844e1dd40f5eb5348d481deca6a
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Reported-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/isofs/inode.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/fs/isofs/inode.c
+++ b/fs/isofs/inode.c
@@ -690,6 +690,11 @@ static int isofs_fill_super(struct super
 	pri_bh = NULL;
 
 root_found:
+	/* We don't support read-write mounts */
+	if (!(s->s_flags & MS_RDONLY)) {
+		error = -EACCES;
+		goto out_freebh;
+	}
 
 	if (joliet_level && (pri == NULL || !opt.rock)) {
 		/* This is the case of Joliet with the norock mount flag.
@@ -1503,9 +1508,6 @@ struct inode *__isofs_iget(struct super_
 static struct dentry *isofs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
-	/* We don't support read-write mounts */
-	if (!(flags & MS_RDONLY))
-		return ERR_PTR(-EACCES);
 	return mount_bdev(fs_type, flags, dev_name, data, isofs_fill_super);
 }
 


Patches currently in stable-queue which might be from jack@suse.cz are

queue-4.4/mm-filemap-don-t-plant-shadow-entries-without-radix-tree-node.patch
queue-4.4/isofs-do-not-return-eacces-for-unknown-filesystems.patch