Re: Double free vulnerability in do_rename_gpt_parts
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 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 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
Re: Double free vulnerability in do_rename_gpt_parts
Am 17.01.2020 um 17:31 schrieb Tom Rini:
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 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!
Ah, yes. I've just responded there.
Regards,
Simon
Re: Double free vulnerability in do_rename_gpt_parts
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 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
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Re: Double free vulnerability in do_rename_gpt_parts
+ Some contributors of this file
On Fri, Jan 17, 2020 at 1:03 PM Jordy 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...
Regards,
Simon
>
> Double freeing may result in a write-what-where condition, allowing an
> attacker to execute arbitrary code.
>
> My advice would be to not free the parition_list on line 702 as nothing is
> being done with it there afterwards anyway and leave your clean_up in the
> out: label :)
>
> Kind Regards,
>
> Jordy Zomer
