Re: [PATCH 00/33] Compile-time stack metadata validation

Chris J Arges
2016-01-22T20:41:03Z

On Fri, Jan 22, 2016 at 01:14:47PM -0600, Josh Poimboeuf wrote:
> On Fri, Jan 22, 2016 at 11:43:48AM -0600, Chris J Arges wrote:
> > On Thu, Jan 21, 2016 at 04:49:04PM -0600, Josh Poimboeuf wrote:
> > > This is v16 of the compile-time stack metadata validation patch set,
> > > along with proposed fixes for most of the warnings it found. It's based
> > > on the tip/master branch.
> > >
> > Josh,
> >
> > Looks good, with my config [1] I do still get a few warnings building
> > linux/linux-next.
> >
> > Here are the warnings:
> > $ grep ^stacktool build.log | grep -v staging
>
> Thanks for reporting these!
>
> > stacktool: arch/x86/kvm/vmx.o: vmx_handle_external_intr()+0x67: call without frame pointer save/setup
>
> This can be fixed by setting the stack pointer as an output operand for
> the inline asm call in vmx_handle_external_intr().
>
> Feel free to submit a patch, or I'll get around to it eventually.
>
> > stacktool: fs/reiserfs/namei.o: set_de_name_and_namelen()+0x9e: return without frame pointer restore
> > stacktool: fs/reiserfs/namei.o: set_de_name_and_namelen()+0x89: duplicate frame pointer save
> > stacktool: fs/reiserfs/namei.o: set_de_name_and_namelen()+0x8a: duplicate frame pointer setup
> > stacktool: fs/reiserfs/namei.o: set_de_name_and_namelen()+0x9e: frame pointer state mismatch
> > stacktool: fs/reiserfs/namei.o: set_de_name_and_namelen()+0x0: frame pointer state mismatch
>
> These are false positives. Stacktool is confused by the use of a
> "noreturn" function which it doesn't know about (__reiserfs_panic).
>
> Unfortunately the only solution I currently have for dealing with global
> noreturn functions is to just hard-code a list of them. So the short
> term fix would be to add "__reiserfs_panic" to the global_noreturns list
> in tools/stacktool/builtin-check.c.
>
> I'm still trying to figure out a better way to deal with this type of
> issue, as it's a pain to have to keep a hard-coded list of noreturn
> functions. Unfortunately that info isn't available in the ELF.
>

Josh,
Ok I'll hack on the patches above.

> > stacktool: fs/reiserfs/ibalance.o: .text: unexpected end of section
> > stacktool: fs/reiserfs/tail_conversion.o: .text: unexpected end of section
>
> For some reason I'm not able to recreate these warnings... Can you
> share one of the .o files?
>
> --
> Josh
>

Binaries are here:
http://people.canonical.com/~arges/stacktool/

--chris