Re: [PATCH AUTOSEL 4.20 43/81] blk-mq: protect debugfs_create_files() from failures

[Greg Kroah-Hartman]

On Thu, Feb 28, 2019 at 10:07:35AM -0500, Sasha Levin wrote:
> From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> 
> [ Upstream commit 36991ca68db9dd43bac7f3519f080ee3939263ef ]
> 
> If debugfs were to return a non-NULL error for a debugfs call, using
> that pointer later in debugfs_create_files() would crash.
> 
> Fix that by properly checking the pointer before referencing it.
> 
> Reported-by: Michal Hocko <mhocko@xxxxxxxxxx>
> Reported-and-tested-by: syzbot+b382ba6a802a3d242790@xxxxxxxxxxxxxxxxxxxxxxxxx
> Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  block/blk-mq-debugfs.c | 3 +++
>  1 file changed, 3 insertions(+)
> 

As the commit this "fixes" should not be backported, no need for this
patch in any stable kernel either.  Please drop from all queues.

thanks,

greg k-h