From b51ce3744f115850166f3d6c292b9c8cb849ad4f Mon Sep 17 00:00:00 2001 From: Gary Hook Date: Mon, 29 Apr 2019 22:22:58 +0000 Subject: x86/mm/mem_encrypt: Disable all instrumentation for early SME setup Enablement of AMD's Secure Memory Encryption feature is determined very early after start_kernel() is entered. Part of this procedure involves scanning the command line for the parameter 'mem_encrypt'. To determine intended state, the function sme_enable() uses library functions cmdline_find_option() and strncmp(). Their use occurs early enough such that it cannot be assumed that any instrumentation subsystem is initialized. For example, making calls to a KASAN-instrumented function before KASAN is set up will result in the use of uninitialized memory and a boot failure. When AMD's SME support is enabled, conditionally disable instrumentation of these dependent functions in lib/string.c and arch/x86/lib/cmdline.c. [ bp: Get rid of intermediary nostackp var and cleanup whitespace. ] Fixes: aca20d546214 ("x86/mm: Add support to make use of Secure Memory Encryption") Reported-by: Li RongQing Signed-off-by: Gary R Hook Signed-off-by: Borislav Petkov Cc: Alexander Shishkin Cc: Andrew Morton Cc: Andy Shevchenko Cc: Boris Brezillon Cc: Coly Li Cc: "dave.hansen@linux.intel.com" Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Kees Cook Cc: Kent Overstreet Cc: "luto@kernel.org" Cc: Masahiro Yamada Cc: Matthew Wilcox Cc: "mingo@redhat.com" Cc: "peterz@infradead.org" Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Cc: x86-ml Link: https://lkml.kernel.org/r/155657657552.7116.18363762932464011367.stgit@sosrh3.amd.com --- lib/Makefile | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'lib') diff --git a/lib/Makefile b/lib/Makefile index 3b08673e8881..18c2be516ab4 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -17,6 +17,17 @@ KCOV_INSTRUMENT_list_debug.o := n KCOV_INSTRUMENT_debugobjects.o := n KCOV_INSTRUMENT_dynamic_debug.o := n +# Early boot use of cmdline, don't instrument it +ifdef CONFIG_AMD_MEM_ENCRYPT +KASAN_SANITIZE_string.o := n + +ifdef CONFIG_FUNCTION_TRACER +CFLAGS_REMOVE_string.o = -pg +endif + +CFLAGS_string.o := $(call cc-option, -fno-stack-protector) +endif + lib-y := ctype.o string.o vsprintf.o cmdline.o \ rbtree.o radix-tree.o timerqueue.o xarray.o \ idr.o int_sqrt.o extable.o \ -- cgit v1.2.3