On Thu, Jun 04, 2020 at 02:58:06PM +0100, Will Deacon wrote: > On Thu, Jun 04, 2020 at 04:49:57PM +0300, Alexander Popov wrote: > > Don't try instrumenting functions in arch/arm64/kernel/vdso/vgettimeofday.c. > > Otherwise that can cause issues if the cleanup pass of stackleak gcc plugin > > is disabled. > > > > Signed-off-by: Alexander Popov <alex.popov@xxxxxxxxx> > > --- > > arch/arm64/kernel/vdso/Makefile | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > > index 3862cad2410c..9b84cafbd2da 100644 > > --- a/arch/arm64/kernel/vdso/Makefile > > +++ b/arch/arm64/kernel/vdso/Makefile > > @@ -32,7 +32,8 @@ UBSAN_SANITIZE := n > > OBJECT_FILES_NON_STANDARD := y > > KCOV_INSTRUMENT := n > > > > -CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables > > +CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables \ > > + $(DISABLE_STACKLEAK_PLUGIN) > > I can pick this one up via arm64, thanks. Are there any other plugins we > should be wary of? It looks like x86 filters out $(GCC_PLUGINS_CFLAGS) > when building the vDSO. I didn't realize/remember that arm64 retained the kernel build flags for vDSO builds. (I'm used to x86 throwing all its flags away for its vDSO.) How does 32-bit ARM do its vDSO? My quick run-through on plugins: arm_ssp_per_task_plugin.c 32-bit ARM only (but likely needs disabling for 32-bit ARM vDSO?) cyc_complexity_plugin.c compile-time reporting only latent_entropy_plugin.c this shouldn't get triggered for the vDSO (no __latent_entropy nor __init attributes in vDSO), but perhaps explicitly disabling it would be a sensible thing to do, just for robustness? randomize_layout_plugin.c this shouldn't get triggered (again, lacking attributes), but should likely be disabled too. sancov_plugin.c This should be tracking the KCOV directly (see scripts/Makefile.kcov), which is already disabled here. structleak_plugin.c This should be fine in the vDSO, but there's not security boundary here, so it wouldn't be important to KEEP it enabled. -- Kees Cook
