On Mon, Oct 07, 2019 at 11:10:18AM +0200, Hans de Goede wrote:
> Hi,
>
> On 07-10-2019 10:50, Hans de Goede wrote:
> > Hi,
> >
> > On 07-10-2019 05:09, Arvind Sankar wrote:
> >> Hi, arch/x86/purgatory/purgatory.ro has an undefined symbol
> >> memzero_explicit. This has come from commit 906a4bb97f5d ("crypto:
> >> sha256 - Use get/put_unaligned_be32 to get input, memzero_explicit")
> >> according to git bisect.
> >
> > Hmm, it (obviously) does build for me and using kexec still also works
> > for me.
> >
> > But it seems that you are right and that this should not build, weird.
>
> Ok, I understand now, it seems that the kernel will happily build with
> undefined symbols in the purgatory and my kexec testing did not hit
> the sha256 check path (*) so it did not crash. I can reproduce this before my
> patch:
Yes -- this should really be fixed. purgatory build should fail if there
are undefined symbols, in fact the Makefile apparently is trying to do
something to catch undefined references?
LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z
nodefaultlib
This doesn't seem to actually do anything though. Anyone know of a way
to force ld to error if the resulting object would have undefined
symbols?
>
> [hans@shalem linux]$ ld arch/x86/purgatory/purgatory.ro
> ld: warning: cannot find entry symbol _start; defaulting to 0000000000401000
> ld: arch/x86/purgatory/purgatory.ro: in function `sha256_transform':
> sha256.c:(.text+0x1c0c): undefined reference to `memzero_explicit'
>
> And I can confirm that it is gone after my patch:
>
> [hans@shalem linux]$ ld arch/x86/purgatory/purgatory.ro
> ld: warning: cannot find entry symbol _start; defaulting to 0000000000401000
>
> Regards,
>
> Hans
>
>
> *) I tried with a Fedora signed kernel, dunno how to trigger this if that
> does not
> trigger it
>
It triggers an error for me when loading the new image, i.e. when doing
# kexec -s -l new_image
Not sure what the difference is, mine is a custom configuration built
using mainline sources.
