On 3/30/20 7:20 PM, Kees Cook wrote:
On Mon, Mar 30, 2020 at 06:17:32PM +0200, Jann Horn wrote:
On Mon, Mar 30, 2020 at 5:59 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
On Mon, Mar 30, 2020 at 8:14 AM Jann Horn <jannh@xxxxxxxxxx> wrote:
I noticed that CONFIG_DEBUG_INFO_BTF seems to partly defeat the point
of CONFIG_GCC_PLUGIN_RANDSTRUCT.
Is it a theoretical stmt or you have data?
I think it's the other way around.
gcc-plugin breaks dwarf and breaks btf.
But I only looked at gcc patches without applying them.
Ah, interesting - I haven't actually tested it, I just assumed
(perhaps incorrectly) that the GCC plugin would deal with DWARF info
properly.
Yeah, GCC appears to create DWARF before the plugin does the
randomization[1], so it's not an exposure, but yes, struct randomization
is pretty completely incompatible with a bunch of things in the kernel
(by design). I'm happy to add negative "depends" in the Kconfig if it
helps clarify anything.
Is this expected to get fixed at some point wrt DWARF? Perhaps would make
sense then to add a negative "depends" for both DWARF and BTF if the option
GCC_PLUGIN_RANDSTRUCT is set given both would be incompatible/broken.
Thanks,
Daniel
-Kees
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052
