On Tue, Aug 14, 2018 at 9:37 AM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, Aug 14, 2018 at 09:24:29AM +0200, Greg KH wrote:
>> On Mon, Aug 13, 2018 at 02:25:12PM -0700, Nick Desaulniers wrote:
>> > On Sat, Aug 11, 2018 at 9:40 AM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>> > >
>> > > On Mon, Aug 06, 2018 at 02:08:32PM -0700, Nick Desaulniers wrote:
>> > > > These patches are needed for kasan+clang support. I confirmed they
>> > > > apply cleanly in order (top to bottom):
>> > > >
>> > > > 4.9:
>> > > > commit c5caf21ab0cf8 ("kasan: turn on -fsanitize-address-use-after-scope")
>> > > > commit 0e410e158e5b ("kasan: don't emit builtin calls when sanitization is off")
>> > >
>> > > By applying these, I get a ton of new build warnings, so I can't add
>> > > them :(
>> >
>> > What? Such innocent patches.
>> >
>> > $ git remote add stable
>> > git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
>> > $ git checkout -b 4.9-stable-kasan stable/linux-4.9.y
>> > <git log shows 4.9.118>
>> > $ git cherry-pick c5caf21ab0cf8
>> > $ git cherry-pick 0e410e158e5b
>> > $ make defconfig
>> > $ make -j46
>> >
>> > I get -Wstringop-truncation, -Wstringop-overflow=,
>> > -Wpacked-not-aligned, -Warray-bounds warnings with gcc-8 with or
>> > without these patches.
>> >
>> > Can you share your config, or what the warning was? Did I checkout
>> > the wrong branch?
>>
>> I used 'make allmodconfig' on a x86 Fedora 27 release which is using gcc
>> 7.3.1. Adding those patches adds a ton of warnings. Let me go do a
>> test build and send you the full log...
>
> Attached is the full build log. Before those 2 patches were added, no
> build warnings. Afterward, I now have 148 build warnings. So something
> is not right here.
I think the issue here is that e7c52b84fb ("kasan: rework Kconfig
settings") should have been backported after c5caf21ab0cf8 ("kasan:
turn on -fsanitize-address-use-after-scope"). You'll need to
"rebackport" the former one (hide use-after-scope under
CONFIG_KASAN_EXTRA and set FRAME_WARN to 3072 with KASAN_EXTRA).
