Re: [PATCH v2] dma-buf: acquire name lock before read/write dma_buf.name

[Christian König]

Am 29.10.21 um 04:15 schrieb guangming.cao@xxxxxxxxxxxx:
> From: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
>
> On Fri, 2021-10-08 at 12:24 +0200, Christian König wrote:
> > Am 08.10.21 um 09:54 schrieb guangming.cao@xxxxxxxxxxxx:
> > > From: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
> > >
> > > Because dma-buf.name can be freed in func: "dma_buf_set_name",
> > > so, we need to acquire lock first before we read/write dma_buf.name
> > > to prevent Use After Free(UAF) issue.
> > >
> > > Signed-off-by: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
> > Reviewed-by: Christian König <christian.koenig@xxxxxxx>
> >
> > Going to push that upstream if nobody else objects.
> >
> > Thanks,
> > Christian.
> Just a gentle ping for this patch, please kindly let me know how is it going.

Ah, yes. Thanks for the reminder.

I've just pushed this to drm-misc-fixes.

Christian.

> > > ---
> > >    drivers/dma-buf/dma-buf.c | 3 +++
> > >    1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > > index 511fe0d217a0..a7f6fd13a635 100644
> > > --- a/drivers/dma-buf/dma-buf.c
> > > +++ b/drivers/dma-buf/dma-buf.c
> > > @@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file
> > > *s, void *unused)
> > >    		if (ret)
> > >    			goto error_unlock;
> > >    
> > > +
> > > +		spin_lock(&buf_obj->name_lock);
> > >    		seq_printf(s,
> > > "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
> > >    				buf_obj->size,
> > >    				buf_obj->file->f_flags, buf_obj->file-
> > > > f_mode,
> > > @@ -1379,6 +1381,7 @@ static int dma_buf_debug_show(struct seq_file
> > > *s, void *unused)
> > >    				buf_obj->exp_name,
> > >    				file_inode(buf_obj->file)->i_ino,
> > >    				buf_obj->name ?: "");
> > > +		spin_unlock(&buf_obj->name_lock);
> > >    
> > >    		robj = buf_obj->resv;
> > >    		fence = dma_resv_excl_fence(robj);
> >
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