Messages in this thread | | | From | Dmitry Vyukov <> | Date | Sat, 23 Feb 2019 11:29:45 +0100 | Subject | Re: [PATCH] kasan: prevent recursive instrumentation |
| |
On Fri, Feb 22, 2019 at 7:29 PM Mark Rutland <mark.rutland@arm.com> wrote: > > When CONFIG_KASAN is selected, <linux/kasan-checks.h> defines the > prototypes for kasan_check_{read,write}(), rather than inline stubs.
+kasan-dev@googlegroups.com
Doesn't this do the same as? https://groups.google.com/d/msg/kasan-dev/NwEdpGgUeac/oXUIRUC6CAAJ
> This is the case even when it is included by files which are not > instrumented by KASAN. Where helpers (e.g. the atomics) are instrumented > with explicit calls to kasan_check_{read,write}(), this results in files > being unexpectedly instrumented. > > This is problematic as it can result in instrumentation in files which > cannot safely call these functions, such as within the EFI stub: > > [mark@lakrids:~/src/linux]% usekorg 8.1.0 make ARCH=arm64 CROSS_COMPILE=aarch64-linux- -j64 -s > drivers/firmware/efi/libstub/arm-stub.stub.o: In function `atomic_set': > /home/mark/src/linux/./include/asm-generic/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write' > /home/mark/src/linux/./include/asm-generic/atomic-instrumented.h:44:(.init.text+0xa0): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `__efistub_kasan_check_write' > Makefile:1021: recipe for target 'vmlinux' failed > make: *** [vmlinux] Error 1 > > Let's avoid this by ensuring that uninstrumented files are given the > same stub definition of these functions used for !KASAN builds. So that > the stub defintions don't conflict with the real definitions in > (uninstrumented) common KASAN code, the real definitions are prefixed > with underscores, and called from unprefixed macros. > > Any compiler-generated instrumentation uses separate > __asan_{load,store}_*() entry points, and is not affected by this > change. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Alexander Potapenko <glider@google.com> > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Ingo Molnar <mingo@kernel.org> > --- > include/linux/kasan-checks.h | 8 +++++--- > mm/kasan/common.c | 8 ++++---- > scripts/Makefile.kasan | 2 +- > 3 files changed, 10 insertions(+), 8 deletions(-) > > Hi, > > Assuming the KASAN folk are happy with this, I'd like this to be queued in the > tip tree, where the arm64 instrumented atomics are already queued. > > Thanks, > Mark. > > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h > index d314150658a4..6cf4b41a5393 100644 > --- a/include/linux/kasan-checks.h > +++ b/include/linux/kasan-checks.h > @@ -2,9 +2,11 @@ > #ifndef _LINUX_KASAN_CHECKS_H > #define _LINUX_KASAN_CHECKS_H > > -#ifdef CONFIG_KASAN > -void kasan_check_read(const volatile void *p, unsigned int size); > -void kasan_check_write(const volatile void *p, unsigned int size); > +#if defined(CONFIG_KASAN) && !defined (KASAN_NOSANITIZE) > +void __kasan_check_read(const volatile void *p, unsigned int size); > +#define kasan_check_read __kasan_check_read > +void __kasan_check_write(const volatile void *p, unsigned int size); > +#define kasan_check_write __kasan_check_write > #else > static inline void kasan_check_read(const volatile void *p, unsigned int size) > { } > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 73c9cbfdedf4..630e32838adb 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -95,17 +95,17 @@ void kasan_disable_current(void) > current->kasan_depth--; > } > > -void kasan_check_read(const volatile void *p, unsigned int size) > +void __kasan_check_read(const volatile void *p, unsigned int size) > { > check_memory_region((unsigned long)p, size, false, _RET_IP_); > } > -EXPORT_SYMBOL(kasan_check_read); > +EXPORT_SYMBOL(__kasan_check_read); > > -void kasan_check_write(const volatile void *p, unsigned int size) > +void __kasan_check_write(const volatile void *p, unsigned int size) > { > check_memory_region((unsigned long)p, size, true, _RET_IP_); > } > -EXPORT_SYMBOL(kasan_check_write); > +EXPORT_SYMBOL(__kasan_check_write); > > #undef memset > void *memset(void *addr, int c, size_t len) > diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan > index 25c259df8ffa..c475a8ac776c 100644 > --- a/scripts/Makefile.kasan > +++ b/scripts/Makefile.kasan > @@ -52,5 +52,5 @@ CFLAGS_KASAN := -fsanitize=kernel-hwaddress \ > endif # CONFIG_KASAN_SW_TAGS > > ifdef CONFIG_KASAN > -CFLAGS_KASAN_NOSANITIZE := -fno-builtin > +CFLAGS_KASAN_NOSANITIZE := -fno-builtin -DKASAN_NOSANITIZE > endif > -- > 2.11.0 >
| |