From: Ard Biesheuvel <ardb@kernel.org>
Date: Tue, 26 Oct 2021 08:23:31 +0000 (+0200)
Subject: ARM: decompressor: disable stack protector
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=672513bf583157cc088a32e75bd850dd9f81564c;p=linux.git

ARM: decompressor: disable stack protector

Enabling the stack protector in the decompressor is of dubious value,
given that it uses a fixed value for the canary, cannot print any output
unless CONFIG_DEBUG_LL is enabled (which relies on board specific build
time settings), and is already disabled for a good chunk of the code
(libfdt).

So let's just disable it in the decompressor. This will make it easier
in the future to manage the command line options that would need to be
removed again in this context for the TLS register based stack
protector.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---

diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index 91265e7ff672f..e2bd084b1cdf0 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -93,11 +93,6 @@ ifeq ($(CONFIG_USE_OF),y)
 OBJS	+= $(libfdt_objs) fdt_check_mem_start.o
 endif
 
-# -fstack-protector-strong triggers protection checks in this code,
-# but it is being used too early to link to meaningful stack_chk logic.
-$(foreach o, $(libfdt_objs) atags_to_fdt.o fdt_check_mem_start.o, \
-	$(eval CFLAGS_$(o) := -I $(srctree)/scripts/dtc/libfdt -fno-stack-protector))
-
 targets       := vmlinux vmlinux.lds piggy_data piggy.o \
 		 lib1funcs.o ashldi3.o bswapsdi2.o \
 		 head.o $(OBJS)
@@ -107,6 +102,7 @@ clean-files += lib1funcs.S ashldi3.S bswapsdi2.S hyp-stub.S
 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
 
 ccflags-y := -fpic $(call cc-option,-mno-single-pic-base,) -fno-builtin \
+	     -I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \
 	     -I$(obj) $(DISABLE_ARM_SSP_PER_TASK_PLUGIN)
 ccflags-remove-$(CONFIG_FUNCTION_TRACER) += -pg
 asflags-y := -DZIMAGE
diff --git a/arch/arm/boot/compressed/misc.c b/arch/arm/boot/compressed/misc.c
index e1e9a5dde853f..c3c66ff2d696b 100644
--- a/arch/arm/boot/compressed/misc.c
+++ b/arch/arm/boot/compressed/misc.c
@@ -128,13 +128,6 @@ asmlinkage void __div0(void)
 	error("Attempting division by 0!");
 }
 
-const unsigned long __stack_chk_guard = 0x000a0dff;
-
-void __stack_chk_fail(void)
-{
-	error("stack-protector: Kernel stack is corrupted\n");
-}
-
 extern int do_decompress(u8 *input, int len, u8 *output, void (*error)(char *x));