From: Brian Gerst Date: Thu, 23 Jan 2025 19:07:35 +0000 (-0500) Subject: x86/boot: Disable stack protector for early boot code X-Git-Tag: v6.15-rc1~216^2~86^2~29 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a9a76b38aaf577887103e3ebb41d70e6aa5a4b19;p=thirdparty%2Fkernel%2Flinux.git x86/boot: Disable stack protector for early boot code On 64-bit, this will prevent crashes when the canary access is changed from %gs:40 to %gs:__stack_chk_guard(%rip). RIP-relative addresses from the identity-mapped early boot code will target the wrong address with zero-based percpu. KASLR could then shift that address to an unmapped page causing a crash on boot. This early boot code runs well before user-space is active and does not need stack protector enabled. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Reviewed-by: Ard Biesheuvel Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250123190747.745588-4-brgerst@gmail.com --- diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index b43eb7e384eba..84cfa179802c3 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -44,6 +44,8 @@ KCOV_INSTRUMENT_unwind_orc.o := n KCOV_INSTRUMENT_unwind_frame.o := n KCOV_INSTRUMENT_unwind_guess.o := n +CFLAGS_head32.o := -fno-stack-protector +CFLAGS_head64.o := -fno-stack-protector CFLAGS_irq.o := -I $(src)/../include/asm/trace obj-y += head_$(BITS).o