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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2019-01-18 11:58:07 +0100
committerKees Cook <keescook@chromium.org>2019-01-20 14:06:40 -0800
commit2c88c742d011707b55da7b54b06a030c6f57233f (patch)
treeed580e8080a047597b44f12afc534adc3dce43c3
parent560706d5d2589ef510f5436d69ab510a351b8cf7 (diff)
gcc-plugins: arm_ssp_per_task_plugin: fix for GCC 9+
GCC 9 reworks the way the references to the stack canary are emitted, to prevent the value from being spilled to the stack before the final comparison in the epilogue, defeating the purpose, given that the spill slot is under control of the attacker that we are protecting ourselves from. Since our canary value address is obtained without accessing memory (as opposed to pre-v7 code that will obtain it from a literal pool), it is unlikely (although not guaranteed) that the compiler will spill the canary value in the same way, so let's just disable this improvement when building with GCC9+. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Kees Cook <keescook@chromium.org>
-rw-r--r--scripts/gcc-plugins/arm_ssp_per_task_plugin.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c
index a65fbefb8501..89c47f57d1ce 100644
--- a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c
+++ b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c
@@ -53,6 +53,19 @@ static unsigned int arm_pertask_ssp_rtl_execute(void)
#define NO_GATE
#include "gcc-generate-rtl-pass.h"
+#if BUILDING_GCC_VERSION >= 9000
+static bool no(void)
+{
+ return false;
+}
+
+static void arm_pertask_ssp_start_unit(void *gcc_data, void *user_data)
+{
+ targetm.have_stack_protect_combined_set = no;
+ targetm.have_stack_protect_combined_test = no;
+}
+#endif
+
__visible int plugin_init(struct plugin_name_args *plugin_info,
struct plugin_gcc_version *version)
{
@@ -100,5 +113,10 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP,
NULL, &arm_pertask_ssp_rtl_pass_info);
+#if BUILDING_GCC_VERSION >= 9000
+ register_callback(plugin_info->base_name, PLUGIN_START_UNIT,
+ arm_pertask_ssp_start_unit, NULL);
+#endif
+
return 0;
}