Double free vulnerability in do_rename_gpt_parts

[Jordy]

Hey Tom,

The patch looks good to me, I do agree with simon that you'd have to initialize the pointers to 0, because uninitialized pointers could contain garbage, unless it's a global variable (those are automagically initialized to 0).


Btw I really appreciate the fast and friendly responses, I've seen that different at other software packages thumbs-up for that!

Best Regards,

Jordy
> On January 17, 2020 11:31 AM Tom Rini <trini at konsulko.com> wrote:
> 
>  
> On Fri, Jan 17, 2020 at 04:29:52PM +0100, Simon Goldschmidt wrote:
> > + Some contributors of this file
> > 
> > On Fri, Jan 17, 2020 at 1:03 PM Jordy <jordy at simplyhacker.com> wrote:
> > >
> > > Hello U-Boot lists!
> > >
> > > I think I found a double free bug in U-Boot, in /cmp/gpt.c in the function do_rename_gpt_parts().
> > >
> > > On line 702 the partition_list is being free'd if ret is smaller than 0.
> > > If the return value is not -ENOMEM it will go to the out: label and free the partition_list again.
> > 
> > Reading the code, I can confirm that. Funny enough, the code in question was
> > introduced by commit 18030d04 ("GPT: fix memory leaks identified by Coverity").
> > Although I think Coverity should have detected the resulting double-free...
> > 
> > However, I'm not sure of the fix: the code just continues for -ENOMEM and then
> > goes on using partitions_list at line 757...
> 
> So, Coverity later did complain about that change (but not immediately,
> funny enough).  I posted http://patchwork.ozlabs.org/patch/1192036/ and
> was hoping for a review on it as it's complex enough I'd like to avoid
> adding a 3rd round of issues there.  Thanks!
> 
> -- 
> Tom