Messages in this thread | | | From | Marco Elver <> | Date | Wed, 18 Oct 2023 18:22:14 +0200 | Subject | Re: [PATCH] lib: Kconfig: disable dynamic sanitizers for test builds |
| |
On Wed, 18 Oct 2023 at 17:32, 'Hamza Mahfooz' via kasan-dev <kasan-dev@googlegroups.com> wrote: > > kasan, kcsan and kmsan all have the tendency to blow up the stack > and there isn't a lot of value in having them enabled for test builds, > since they are intended to be useful for runtime debugging. So, disable > them for test builds. > > Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com> > --- > lib/Kconfig.kasan | 1 + > lib/Kconfig.kcsan | 1 + > lib/Kconfig.kmsan | 1 + > 3 files changed, 3 insertions(+)
Do you have links to discussions that motivate this change? This has been discussed in the past. One recommendation is to adjust the build/test scripts to exclude some combination of configs if they are causing issues. Or we increase CONFIG_FRAME_WARN if one of them is enabled (KMSAN sets it to 0, 32-bit KASAN increases it a bit).
That being said, we're aware of KASAN having had more issues and there are some suboptions that have been disabled because of that (like KASAN_STACK). I'm not sure if Clang's KASAN instrumentation has had some recent improvements (we did investigate it, but I can't recall what the outcome was [1]) - maybe try a more recent compiler? However, KCSAN and KMSAN shouldn't have any issues (if KMSAN is enabled, FRAME_WARN is 0). And having build tests with them enabled isn't useless at all: we're making sure that these tools (even though only for debugging), still work. We _want_ them to work during random build testing!
Please share the concrete problem you're having, because this change will make things worse for everyone in the long run.
[1] https://github.com/llvm/llvm-project/issues/38157
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan > index fdca89c05745..fbd85c4872c0 100644 > --- a/lib/Kconfig.kasan > +++ b/lib/Kconfig.kasan > @@ -38,6 +38,7 @@ menuconfig KASAN > CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \ > HAVE_ARCH_KASAN_HW_TAGS > depends on (SLUB && SYSFS && !SLUB_TINY) || (SLAB && !DEBUG_SLAB) > + depends on !COMPILE_TEST > select STACKDEPOT_ALWAYS_INIT > help > Enables KASAN (Kernel Address Sanitizer) - a dynamic memory safety
This also disables KASAN_HW_TAGS, which is actually enabled in production kernels and does not use any compiler instrumentation.
> diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan > index 609ddfc73de5..7bcefdbfb46f 100644 > --- a/lib/Kconfig.kcsan > +++ b/lib/Kconfig.kcsan > @@ -14,6 +14,7 @@ menuconfig KCSAN > bool "KCSAN: dynamic data race detector" > depends on HAVE_ARCH_KCSAN && HAVE_KCSAN_COMPILER > depends on DEBUG_KERNEL && !KASAN > + depends on !COMPILE_TEST > select CONSTRUCTORS > select STACKTRACE > help > diff --git a/lib/Kconfig.kmsan b/lib/Kconfig.kmsan > index ef2c8f256c57..eb05c885d3fd 100644 > --- a/lib/Kconfig.kmsan > +++ b/lib/Kconfig.kmsan > @@ -13,6 +13,7 @@ config KMSAN > depends on HAVE_ARCH_KMSAN && HAVE_KMSAN_COMPILER > depends on SLUB && DEBUG_KERNEL && !KASAN && !KCSAN > depends on !PREEMPT_RT > + depends on !COMPILE_TEST
KMSAN already selects FRAME_WARN of 0 and should not cause you any issues during build testing.
Nack.
| |