The patch titled
Subject: kcov: don't instrument with UBSAN
has been added to the -mm tree. Its filename is
kcov-dont-instrument-with-ubsan.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kcov-dont-instrument-with-ubsan.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kcov-dont-instrument-with-ubsan.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Subject: kcov: don't instrument with UBSAN
Both KCOV and UBSAN use compiler instrumentation. If UBSAN detects a bug
in KCOV, it may cause infinite recursion via printk and other common
functions. We already don't instrument KCOV with KASAN/KCSAN for this
reason, don't instrument it with UBSAN as well.
As a side effect this also resolves the following gcc warning:
conflicting types for built-in function '__sanitizer_cov_trace_switch';
expected 'void(long unsigned int, void *)'
[-Wbuiltin-declaration-mismatch]
It's only reported when kcov.c is compiled with any of the sanitizers
enabled. Size of the arguments is correct, it's just that gcc uses 'long'
on 64-bit arches and 'long long' on 32-bit arches, while kernel type is
always 'long long'.
Link: https://lkml.kernel.org/r/20201209100152.2492072-1-dvyukov@xxxxxxxxxx
Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Suggested-by: Marco Elver <elver@xxxxxxxxxx>
Acked-by: Marco Elver <elver@xxxxxxxxxx>
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/Makefile | 3 +++
1 file changed, 3 insertions(+)
--- a/kernel/Makefile~kcov-dont-instrument-with-ubsan
+++ a/kernel/Makefile
@@ -34,8 +34,11 @@ KCOV_INSTRUMENT_extable.o := n
KCOV_INSTRUMENT_stacktrace.o := n
# Don't self-instrument.
KCOV_INSTRUMENT_kcov.o := n
+# If sanitizers detect any issues in kcov, it may lead to recursion
+# via printk, etc.
KASAN_SANITIZE_kcov.o := n
KCSAN_SANITIZE_kcov.o := n
+UBSAN_SANITIZE_kcov.o := n
CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector
obj-y += sched/
_
Patches currently in -mm which might be from dvyukov@xxxxxxxxxx are
kcov-dont-instrument-with-ubsan.patch
