Re: [PATCH 5/5] gcc-plugins/stackleak: Don't instrument vgettimeofday.c in arm64 VDSO
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From: Kees Cook <hidden>
Date: 2020-06-09 19:09:34
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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:quoted
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 <redacted> --- 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel