Re: [PATCH 01/14] misc: fastrpc: Fix use-after-free and race in fastrpc_map_find

[Greg Kroah-Hartman]

On Fri, Sep 02, 2022 at 04:13:31PM +0300, Abel Vesa wrote:
> Currently, there is a race window between the point when the mutex is
> unlocked in fastrpc_map_lookup and the reference count increasing
> (fastrpc_map_get) in fastrpc_map_find, which can also lead to
> use-after-free.
> 
> So lets merge fastrpc_map_find into fastrpc_map_lookup which allows us
> to both protect the maps list by also taking the &fl->lock spinlock and
> the reference count, since the spinlock will be released only after.
> Add take_ref argument to make this suitable for all callers.
> 
> Co-developed-by: Ola Jeppsson <ola@xxxxxxxx>
> Signed-off-by: Ola Jeppsson <ola@xxxxxxxx>
> Signed-off-by: Abel Vesa <abel.vesa@xxxxxxxxxx>
> ---
>  drivers/misc/fastrpc.c | 41 +++++++++++++++++++++--------------------
>  1 file changed, 21 insertions(+), 20 deletions(-)

What commit does this fix?  Should it go to stable trees?

Try splitting this series up into 2, one for 6.0-final with bugfixes to
resolve issues found, and the next one on top of that for new features.

thanks,

greg k-h