Re: fs: gpf in simple_setattr

[Jan Kara <jack@suse.cz>]

On Tue 04-03-14 19:00:32, Sasha Levin wrote:
> On 03/03/2014 04:40 PM, Jan Kara wrote:
> >On Sat 01-03-14 15:05:21, Sasha Levin wrote:
> >>>ping again?
> >>>
> >>>I've been working on it, but don't see an obvious issue.
> >>>
> >>>It does look like an access to invalid memory easily doable from
> >>>userspace, so it should probably get fixed soon...
> >   Hum, can you maybe dump the name in dentry passed to simple_setattr()? Or
> >maybe even the whole path using dentry_path() (but not sure if that will
> >be workable on half-torn-down fs)? Maybe it will give us a hint at which
> >filesystem to look...
> 
> It's just garbage, this is why I'm having a hard time making any progress with
> this bug.
  OK, but that is strange because we hold a reference to the dentry so
noone should free it. So dentry->d_name should be valid... Is the rest of
the dentry also garbage? E.g. does dentry->d_inode still point to the inode
we call __mark_inode_dirty() on? Is dentry->d_sb == dentry->d_inode->i_sb?
Also if the inode isn't completely garbage, we can maybe infer something
from inode->i_op - that should point to some statically allocated
operations struct so we should be able to guess fs type from that.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR