[PATCH 3.10 175/319] isofs: Do not return EACCES for unknown filesystems

Willy Tarreau
2017-02-05T20:00:19Z

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: Willy Tarreau <w@1wt.eu>
---
fs/isofs/inode.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c
index 10489bb..955fabf 100644
--- a/fs/isofs/inode.c
+++ b/fs/isofs/inode.c
@@ -726,6 +726,11 @@ static int isofs_fill_super(struct super_block *s, void *data, int silent)
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.
@@ -1538,9 +1543,6 @@ struct inode *__isofs_iget(struct super_block *sb,
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);
}

--
2.8.0.rc2.1.gbe9624a