The following commit has been merged into the x86/seves branch of tip:
Commit-ID: 103a4908ad4da9decdf9bc7216ec5a4861edf703
Gitweb:
https://git.kernel.org/tip/103a4908ad4da9decdf9bc7216ec5a4861edf703
Author: Arvind Sankar <nived...@alum.mit.edu>
AuthorDate: Thu, 08 Oct 2020 15:16:23 -04:00
Committer: Borislav Petkov <b...@suse.de>
CommitterDate: Mon, 19 Oct 2020 13:11:00 +02:00
x86/head/64: Disable stack protection for head$(BITS).o
On 64-bit, the startup_64_setup_env() function added in
866b556efa12 ("x86/head/64: Install startup GDT")
has stack protection enabled because of set_bringup_idt_handler().
This happens when CONFIG_STACKPROTECTOR_STRONG is enabled. It
also currently needs CONFIG_AMD_MEM_ENCRYPT enabled because then
set_bringup_idt_handler() is not an empty stub but that might change in
the future, when the other vendor adds their similar technology.
At this point, %gs is not yet initialized, and this doesn't cause a
crash only because the #PF handler from the decompressor stub is still
installed and handles the page fault.
Disable stack protection for the whole file, and do it on 32-bit as
well to avoid surprises.
[ bp: Extend commit message with the exact explanation how it happens. ]
Signed-off-by: Arvind Sankar <nived...@alum.mit.edu>
Signed-off-by: Borislav Petkov <b...@suse.de>
Reviewed-by: Joerg Roedel <jroe...@suse.de>
Link: https://lkml.kernel.org/r/20201008191623.2881677-6-nived...@alum.mit.edu
---
arch/x86/kernel/Makefile | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 04ceea8..68608bd 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -47,6 +47,8 @@ endif
# non-deterministic coverage.
KCOV_INSTRUMENT := n
+CFLAGS_head$(BITS).o += -fno-stack-protector
+
CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
obj-y := process_$(BITS).o signal.o
