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 we can't assume 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.
Fixes: aca20d546214 ("x86/mm: Add support to make use of Secure Memory Encryption")
Reported-by: Li RongQing <[email protected]>
Signed-off-by: Gary R Hook <[email protected]>
---
arch/x86/lib/Makefile | 16 ++++++++++++++++
lib/Makefile | 14 ++++++++++++++
2 files changed, 30 insertions(+)
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 140e61843a07..b5b932124280 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -6,6 +6,22 @@
# Produces uninteresting flaky coverage.
KCOV_INSTRUMENT_delay.o := n
+ifdef CONFIG_AMD_MEM_ENCRYPT
+#
+# Early boot use of cmdline; don't instrument it
+#
+KCOV_INSTRUMENT_cmdline.o := n
+
+KASAN_SANITIZE_cmdline.o := n
+
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_cmdline.o = -pg
+endif
+
+nostackp := $(call cc-option, -fno-stack-protector)
+CFLAGS_cmdline.o := $(nostackp)
+endif
+
inat_tables_script = $(srctree)/arch/x86/tools/gen-insn-attr-x86.awk
inat_tables_maps = $(srctree)/arch/x86/lib/x86-opcode-map.txt
quiet_cmd_inat_tables = GEN $@
diff --git a/lib/Makefile b/lib/Makefile
index 3b08673e8881..07d71662f6b2 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -17,6 +17,20 @@ KCOV_INSTRUMENT_list_debug.o := n
KCOV_INSTRUMENT_debugobjects.o := n
KCOV_INSTRUMENT_dynamic_debug.o := n
+ifdef CONFIG_AMD_MEM_ENCRYPT
+#
+# Early boot use of cmdline, don't instrument it
+#
+KASAN_SANITIZE_string.o := n
+
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_string.o = -pg
+endif
+
+nostackp := $(call cc-option, -fno-stack-protector)
+CFLAGS_string.o := $(nostackp)
+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 \
Commit-ID: b51ce3744f115850166f3d6c292b9c8cb849ad4f
Gitweb: https://git.kernel.org/tip/b51ce3744f115850166f3d6c292b9c8cb849ad4f
Author: Gary Hook <[email protected]>
AuthorDate: Mon, 29 Apr 2019 22:22:58 +0000
Committer: Borislav Petkov <[email protected]>
CommitDate: Tue, 30 Apr 2019 17:59:08 +0200
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 <[email protected]>
Signed-off-by: Gary R Hook <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Boris Brezillon <[email protected]>
Cc: Coly Li <[email protected]>
Cc: "[email protected]" <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: "[email protected]" <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: "[email protected]" <[email protected]>
Cc: "[email protected]" <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: x86-ml <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
---
arch/x86/lib/Makefile | 12 ++++++++++++
lib/Makefile | 11 +++++++++++
2 files changed, 23 insertions(+)
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 140e61843a07..3cb3af51ec89 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -6,6 +6,18 @@
# Produces uninteresting flaky coverage.
KCOV_INSTRUMENT_delay.o := n
+# Early boot use of cmdline; don't instrument it
+ifdef CONFIG_AMD_MEM_ENCRYPT
+KCOV_INSTRUMENT_cmdline.o := n
+KASAN_SANITIZE_cmdline.o := n
+
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_cmdline.o = -pg
+endif
+
+CFLAGS_cmdline.o := $(call cc-option, -fno-stack-protector)
+endif
+
inat_tables_script = $(srctree)/arch/x86/tools/gen-insn-attr-x86.awk
inat_tables_maps = $(srctree)/arch/x86/lib/x86-opcode-map.txt
quiet_cmd_inat_tables = GEN $@
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 \