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

Josh Poimboeuf
2016-01-22T19:14:57Z

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.

> 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