2022-07-01 14:36:32

by Alexander Potapenko

Subject: [PATCH v4 12/45] kmsan: disable instrumentation of unsupported common kernel code

EFI stub cannot be linked with KMSAN runtime, so we disable
instrumentation for it.

Instrumenting kcov, stackdepot or lockdep leads to infinite recursion
caused by instrumentation hooks calling instrumented code again.

This patch was previously part of "kmsan: disable KMSAN instrumentation
for certain kernel parts", but was split away per Mark Rutland's
request.

Signed-off-by: Alexander Potapenko <[email protected]>
---
Link: https://linux-review.googlesource.com/id/I41ae706bd3474f074f6a870bfc3f0f90e9c720f7
---
drivers/firmware/efi/libstub/Makefile | 1 +
kernel/Makefile | 1 +
kernel/locking/Makefile | 3 ++-
lib/Makefile | 1 +
4 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index d0537573501e9..81432d0c904b1 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -46,6 +46,7 @@ GCOV_PROFILE := n
# Sanitizer runtimes are unavailable and cannot be linked here.
KASAN_SANITIZE := n
KCSAN_SANITIZE := n
+KMSAN_SANITIZE := n
UBSAN_SANITIZE := n
OBJECT_FILES_NON_STANDARD := y

diff --git a/kernel/Makefile b/kernel/Makefile
index a7e1f49ab2b3b..e47f0526c987f 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -38,6 +38,7 @@ KCOV_INSTRUMENT_kcov.o := n
KASAN_SANITIZE_kcov.o := n
KCSAN_SANITIZE_kcov.o := n
UBSAN_SANITIZE_kcov.o := n
+KMSAN_SANITIZE_kcov.o := n
CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector

# Don't instrument error handlers
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index d51cabf28f382..ea925731fa40f 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -5,8 +5,9 @@ KCOV_INSTRUMENT := n

obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o

-# Avoid recursion lockdep -> KCSAN -> ... -> lockdep.
+# Avoid recursion lockdep -> sanitizer -> ... -> lockdep.
KCSAN_SANITIZE_lockdep.o := n
+KMSAN_SANITIZE_lockdep.o := n

ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)
diff --git a/lib/Makefile b/lib/Makefile
index f99bf61f8bbc6..5056769d00bb6 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -272,6 +272,7 @@ obj-$(CONFIG_POLYNOMIAL) += polynomial.o
CFLAGS_stackdepot.o += -fno-builtin
obj-$(CONFIG_STACKDEPOT) += stackdepot.o
KASAN_SANITIZE_stackdepot.o := n
+KMSAN_SANITIZE_stackdepot.o := n
KCOV_INSTRUMENT_stackdepot.o := n

obj-$(CONFIG_REF_TRACKER) += ref_tracker.o
--
2.37.0.rc0.161.g10f37bed90-goog

2022-07-12 12:17:01

by Marco Elver

Subject: Re: [PATCH v4 12/45] kmsan: disable instrumentation of unsupported common kernel code

On Fri, 1 Jul 2022 at 16:23, Alexander Potapenko <[email protected]> wrote:
>
> EFI stub cannot be linked with KMSAN runtime, so we disable
> instrumentation for it.
>
> Instrumenting kcov, stackdepot or lockdep leads to infinite recursion
> caused by instrumentation hooks calling instrumented code again.
>
> This patch was previously part of "kmsan: disable KMSAN instrumentation
> for certain kernel parts", but was split away per Mark Rutland's
> request.

The "This patch..." paragraph feels out of place, and feels like it
should be part of a v4 changelog below ---.

> Signed-off-by: Alexander Potapenko <[email protected]>

Otherwise,

Reviewed-by: Marco Elver <[email protected]>

> ---
> Link: https://linux-review.googlesource.com/id/I41ae706bd3474f074f6a870bfc3f0f90e9c720f7
> ---
> drivers/firmware/efi/libstub/Makefile | 1 +
> kernel/Makefile | 1 +
> kernel/locking/Makefile | 3 ++-
> lib/Makefile | 1 +
> 4 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index d0537573501e9..81432d0c904b1 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -46,6 +46,7 @@ GCOV_PROFILE := n
> # Sanitizer runtimes are unavailable and cannot be linked here.
> KASAN_SANITIZE := n
> KCSAN_SANITIZE := n
> +KMSAN_SANITIZE := n
> UBSAN_SANITIZE := n
> OBJECT_FILES_NON_STANDARD := y
>
> diff --git a/kernel/Makefile b/kernel/Makefile
> index a7e1f49ab2b3b..e47f0526c987f 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -38,6 +38,7 @@ KCOV_INSTRUMENT_kcov.o := n
> KASAN_SANITIZE_kcov.o := n
> KCSAN_SANITIZE_kcov.o := n
> UBSAN_SANITIZE_kcov.o := n
> +KMSAN_SANITIZE_kcov.o := n
> CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector
>
> # Don't instrument error handlers
> diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
> index d51cabf28f382..ea925731fa40f 100644
> --- a/kernel/locking/Makefile
> +++ b/kernel/locking/Makefile
> @@ -5,8 +5,9 @@ KCOV_INSTRUMENT := n
>
> obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o
>
> -# Avoid recursion lockdep -> KCSAN -> ... -> lockdep.
> +# Avoid recursion lockdep -> sanitizer -> ... -> lockdep.
> KCSAN_SANITIZE_lockdep.o := n
> +KMSAN_SANITIZE_lockdep.o := n
>
> ifdef CONFIG_FUNCTION_TRACER
> CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)
> diff --git a/lib/Makefile b/lib/Makefile
> index f99bf61f8bbc6..5056769d00bb6 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -272,6 +272,7 @@ obj-$(CONFIG_POLYNOMIAL) += polynomial.o
> CFLAGS_stackdepot.o += -fno-builtin
> obj-$(CONFIG_STACKDEPOT) += stackdepot.o
> KASAN_SANITIZE_stackdepot.o := n
> +KMSAN_SANITIZE_stackdepot.o := n
> KCOV_INSTRUMENT_stackdepot.o := n
>
> obj-$(CONFIG_REF_TRACKER) += ref_tracker.o
> --
> 2.37.0.rc0.161.g10f37bed90-goog
>