From 103a4908ad4da9decdf9bc7216ec5a4861edf703 Mon Sep 17 00:00:00 2001 From: Arvind Sankar Date: Thu, 8 Oct 2020 15:16:23 -0400 Subject: [PATCH] x86/head/64: Disable stack protection for head$(BITS).o On 64-bit, the startup_64_setup_env() function added in 866b556efa12 ("x86/head/64: Install startup GDT") has stack protection enabled because of set_bringup_idt_handler(). This happens when CONFIG_STACKPROTECTOR_STRONG is enabled. It also currently needs CONFIG_AMD_MEM_ENCRYPT enabled because then set_bringup_idt_handler() is not an empty stub but that might change in the future, when the other vendor adds their similar technology. At this point, %gs is not yet initialized, and this doesn't cause a crash only because the #PF handler from the decompressor stub is still installed and handles the page fault. Disable stack protection for the whole file, and do it on 32-bit as well to avoid surprises. [ bp: Extend commit message with the exact explanation how it happens. ] Signed-off-by: Arvind Sankar Signed-off-by: Borislav Petkov Reviewed-by: Joerg Roedel Link: https://lkml.kernel.org/r/20201008191623.2881677-6-nivedita@alum.mit.edu --- arch/x86/kernel/Makefile | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 04ceea8..68608bd 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -47,6 +47,8 @@ endif # non-deterministic coverage. KCOV_INSTRUMENT := n +CFLAGS_head$(BITS).o += -fno-stack-protector + CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace obj-y := process_$(BITS).o signal.o -- 2.7.4