Messages in this thread | | | Date | Mon, 7 Jun 2021 11:48:06 +0100 | From | Luis Henriques <> | Subject | Re: [RFC PATCH] gcov: add basic gcov_info validation to gcov initialization |
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On Mon, Jun 07, 2021 at 11:59:45AM +0200, Peter Oberparleiter wrote: > On 02.06.2021 12:24, Luis Henriques wrote: > > Add a basic gcov_info struct validation helper to gcc to ensure we have > > sane from the compiler. > > > > Signed-off-by: Luis Henriques <lhenriques@suse.de> > > --- > > Hi! > > > > I know this won't really validate the gcov_info struct, but it will at > > least prevent kernel crashes in simple scenarios (such as the one I'm > > seeing with gcc 9.3.1). > > Thanks for your suggestion of adding validity checking for the gcov_info > struct. The goal you aim at is definitely something that we want to have > to reduce the impact of fallout from changes to GCC's gcov_info struct. > > In my opinion though the approach you described - looking at the > contents of specific fields in gcov_info - isn't the correct way to go > forward. Since you cannot know how gcov_info changed, accessing any data > in it is very dangerous. Even if there's no out-of-bounds access (if the > struct's size was reduced) the field you are checking could have moved > elsewhere so the meaningfulness of the check is very limited. > > In a previous discussion on the same topic I proposed a different > approach for a build-time check that would fully check the compatibility > of kernel code and GCC-emitted gcov-related data structures. See: > > https://lore.kernel.org/patchwork/patch/1393585/#1592411 >
Thanks, I see the problem is way more complex and I understand that my patch is just wrong. Thanks for pointing me at this thread.
> Unfortunately I have not yet found the time to implement this approach > but it's still on my to-do-list. > > Regarding the cause of the error you're seeing I'll have a look at the > corresponding GCC source to see if there's anything that could be > causing the issue.
Great, thanks. Let me know if you need me to provide more info or testing. I'll be glad to help.
Cheers, -- Luís
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