| Message ID | 20211013150025.2875883-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [1/2] kasan: test: use underlying string helpers | expand |
On 10/13/21 5:00 PM, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > Calling memcmp() and memchr() with an intentional buffer overflow > is now caught at compile time: > > In function 'memcmp', > inlined from 'kasan_memcmp' at lib/test_kasan.c:897:2: > include/linux/fortify-string.h:263:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > 263 | __read_overflow(); > | ^~~~~~~~~~~~~~~~~ > In function 'memchr', > inlined from 'kasan_memchr' at lib/test_kasan.c:872:2: > include/linux/fortify-string.h:277:17: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > 277 | __read_overflow(); > | ^~~~~~~~~~~~~~~~~ > > Change the kasan tests to wrap those inside of a noinline function > to prevent the compiler from noticing the bug and let kasan find > it at runtime. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > --- > lib/test_kasan.c | 19 +++++++++++++++++-- > 1 file changed, 17 insertions(+), 2 deletions(-) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index 67ed689a0b1b..903215e944f1 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -852,6 +852,21 @@ static void kmem_cache_invalid_free(struct kunit *test) > kmem_cache_destroy(cache); > } > > +/* > + * noinline wrappers to prevent the compiler from noticing the overflow > + * at compile time rather than having kasan catch it. > + * */ > +static noinline void *__kasan_memchr(const void *s, int c, size_t n) > +{ > + return memchr(s, c, n); > +} > + > +static noinline int __kasan_memcmp(const void *s1, const void *s2, size_t n) > +{ > + return memcmp(s1, s2, n); > +} > + > + > static void kasan_memchr(struct kunit *test) > { > char *ptr; > @@ -870,7 +885,7 @@ static void kasan_memchr(struct kunit *test) > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > > KUNIT_EXPECT_KASAN_FAIL(test, > - kasan_ptr_result = memchr(ptr, '1', size + 1)); > + kasan_ptr_result = __kasan_memchr(ptr, '1', size + 1)); > > kfree(ptr); > } > @@ -895,7 +910,7 @@ static void kasan_memcmp(struct kunit *test) > memset(arr, 0, sizeof(arr)); > > KUNIT_EXPECT_KASAN_FAIL(test, > - kasan_int_result = memcmp(ptr, arr, size+1)); > + kasan_int_result = __kasan_memcmp(ptr, arr, size+1)); > kfree(ptr); > } > >
On October 14, 2021 1:12:54 AM PDT, Vincenzo Frascino <vincenzo.frascino@arm.com> wrote: > > >On 10/13/21 5:00 PM, Arnd Bergmann wrote: >> From: Arnd Bergmann <arnd@arndb.de> >> >> Calling memcmp() and memchr() with an intentional buffer overflow >> is now caught at compile time: >> >> In function 'memcmp', >> inlined from 'kasan_memcmp' at lib/test_kasan.c:897:2: >> include/linux/fortify-string.h:263:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) >> 263 | __read_overflow(); >> | ^~~~~~~~~~~~~~~~~ >> In function 'memchr', >> inlined from 'kasan_memchr' at lib/test_kasan.c:872:2: >> include/linux/fortify-string.h:277:17: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) >> 277 | __read_overflow(); >> | ^~~~~~~~~~~~~~~~~ >> >> Change the kasan tests to wrap those inside of a noinline function >> to prevent the compiler from noticing the bug and let kasan find >> it at runtime. >> >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > >Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> How about just explicitly making the size invisible to the compiler? I did this for similar issues in the same source: https://lore.kernel.org/linux-hardening/20211006181544.1670992-1-keescook@chromium.org/T/#u -Kees > >> --- >> lib/test_kasan.c | 19 +++++++++++++++++-- >> 1 file changed, 17 insertions(+), 2 deletions(-) >> >> diff --git a/lib/test_kasan.c b/lib/test_kasan.c >> index 67ed689a0b1b..903215e944f1 100644 >> --- a/lib/test_kasan.c >> +++ b/lib/test_kasan.c >> @@ -852,6 +852,21 @@ static void kmem_cache_invalid_free(struct kunit *test) >> kmem_cache_destroy(cache); >> } >> >> +/* >> + * noinline wrappers to prevent the compiler from noticing the overflow >> + * at compile time rather than having kasan catch it. >> + * */ >> +static noinline void *__kasan_memchr(const void *s, int c, size_t n) >> +{ >> + return memchr(s, c, n); >> +} >> + >> +static noinline int __kasan_memcmp(const void *s1, const void *s2, size_t n) >> +{ >> + return memcmp(s1, s2, n); >> +} >> + >> + >> static void kasan_memchr(struct kunit *test) >> { >> char *ptr; >> @@ -870,7 +885,7 @@ static void kasan_memchr(struct kunit *test) >> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); >> >> KUNIT_EXPECT_KASAN_FAIL(test, >> - kasan_ptr_result = memchr(ptr, '1', size + 1)); >> + kasan_ptr_result = __kasan_memchr(ptr, '1', size + 1)); >> >> kfree(ptr); >> } >> @@ -895,7 +910,7 @@ static void kasan_memcmp(struct kunit *test) >> memset(arr, 0, sizeof(arr)); >> >> KUNIT_EXPECT_KASAN_FAIL(test, >> - kasan_int_result = memcmp(ptr, arr, size+1)); >> + kasan_int_result = __kasan_memcmp(ptr, arr, size+1)); >> kfree(ptr); >> } >> >> >
On Wed, Oct 13, 2021 at 05:00:05PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > Calling memcmp() and memchr() with an intentional buffer overflow > is now caught at compile time: > > In function 'memcmp', > inlined from 'kasan_memcmp' at lib/test_kasan.c:897:2: > include/linux/fortify-string.h:263:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > 263 | __read_overflow(); > | ^~~~~~~~~~~~~~~~~ > In function 'memchr', > inlined from 'kasan_memchr' at lib/test_kasan.c:872:2: > include/linux/fortify-string.h:277:17: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > 277 | __read_overflow(); > | ^~~~~~~~~~~~~~~~~ > > Change the kasan tests to wrap those inside of a noinline function > to prevent the compiler from noticing the bug and let kasan find > it at runtime. Is this with W=1 ? I had explicitly disabled the read overflows for "phase 1" of the overflow restriction tightening... (And what do you think of using OPTIMIZER_HIDE_VAR() instead[1]? -Kees [1] https://lore.kernel.org/linux-hardening/20211006181544.1670992-1-keescook@chromium.org/T/#u > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > lib/test_kasan.c | 19 +++++++++++++++++-- > 1 file changed, 17 insertions(+), 2 deletions(-) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index 67ed689a0b1b..903215e944f1 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -852,6 +852,21 @@ static void kmem_cache_invalid_free(struct kunit *test) > kmem_cache_destroy(cache); > } > > +/* > + * noinline wrappers to prevent the compiler from noticing the overflow > + * at compile time rather than having kasan catch it. > + * */ > +static noinline void *__kasan_memchr(const void *s, int c, size_t n) > +{ > + return memchr(s, c, n); > +} > + > +static noinline int __kasan_memcmp(const void *s1, const void *s2, size_t n) > +{ > + return memcmp(s1, s2, n); > +} > + > + > static void kasan_memchr(struct kunit *test) > { > char *ptr; > @@ -870,7 +885,7 @@ static void kasan_memchr(struct kunit *test) > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > > KUNIT_EXPECT_KASAN_FAIL(test, > - kasan_ptr_result = memchr(ptr, '1', size + 1)); > + kasan_ptr_result = __kasan_memchr(ptr, '1', size + 1)); > > kfree(ptr); > } > @@ -895,7 +910,7 @@ static void kasan_memcmp(struct kunit *test) > memset(arr, 0, sizeof(arr)); > > KUNIT_EXPECT_KASAN_FAIL(test, > - kasan_int_result = memcmp(ptr, arr, size+1)); > + kasan_int_result = __kasan_memcmp(ptr, arr, size+1)); > kfree(ptr); > } > > -- > 2.29.2 >
On Mon, Oct 18, 2021 at 9:47 PM Kees Cook <keescook@chromium.org> wrote: > On Wed, Oct 13, 2021 at 05:00:05PM +0200, Arnd Bergmann wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > > > Calling memcmp() and memchr() with an intentional buffer overflow > > is now caught at compile time: > > > > In function 'memcmp', > > inlined from 'kasan_memcmp' at lib/test_kasan.c:897:2: > > include/linux/fortify-string.h:263:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > > 263 | __read_overflow(); > > | ^~~~~~~~~~~~~~~~~ > > In function 'memchr', > > inlined from 'kasan_memchr' at lib/test_kasan.c:872:2: > > include/linux/fortify-string.h:277:17: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > > 277 | __read_overflow(); > > | ^~~~~~~~~~~~~~~~~ > > > > Change the kasan tests to wrap those inside of a noinline function > > to prevent the compiler from noticing the bug and let kasan find > > it at runtime. > > Is this with W=1 ? I had explicitly disabled the read overflows for > "phase 1" of the overflow restriction tightening... I have a somewhat modified source tree that builds cleanly with W=1 after disabling all the noisy ones, so this is probably one that I would not have seen without it. > (And what do you think of using OPTIMIZER_HIDE_VAR() instead[1]? > > [1] https://lore.kernel.org/linux-hardening/20211006181544.1670992-1-keescook@chromium.org/T/#u Yes, that is probably better. I can try updating the patch tomorrow, unless you do it first. Arnd
On Thu, 14 Oct 2021 19:40:45 -0700 Kees Cook <keescook@chromium.org> wrote: > > > On October 14, 2021 1:12:54 AM PDT, Vincenzo Frascino <vincenzo.frascino@arm.com> wrote: > > > > > >On 10/13/21 5:00 PM, Arnd Bergmann wrote: > >> From: Arnd Bergmann <arnd@arndb.de> > >> > >> Calling memcmp() and memchr() with an intentional buffer overflow > >> is now caught at compile time: > >> > >> In function 'memcmp', > >> inlined from 'kasan_memcmp' at lib/test_kasan.c:897:2: > >> include/linux/fortify-string.h:263:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > >> 263 | __read_overflow(); > >> | ^~~~~~~~~~~~~~~~~ > >> In function 'memchr', > >> inlined from 'kasan_memchr' at lib/test_kasan.c:872:2: > >> include/linux/fortify-string.h:277:17: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > >> 277 | __read_overflow(); > >> | ^~~~~~~~~~~~~~~~~ > >> > >> Change the kasan tests to wrap those inside of a noinline function > >> to prevent the compiler from noticing the bug and let kasan find > >> it at runtime. > >> > >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > > >Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > > How about just explicitly making the size invisible to the compiler? > > I did this for similar issues in the same source: > > https://lore.kernel.org/linux-hardening/20211006181544.1670992-1-keescook@chromium.org/T/#u > Arnd?
On Thu, Oct 28, 2021 at 01:15:26PM -0700, Andrew Morton wrote: > On Thu, 14 Oct 2021 19:40:45 -0700 Kees Cook <keescook@chromium.org> wrote: > > > > > > > On October 14, 2021 1:12:54 AM PDT, Vincenzo Frascino <vincenzo.frascino@arm.com> wrote: > > > > > > > > >On 10/13/21 5:00 PM, Arnd Bergmann wrote: > > >> From: Arnd Bergmann <arnd@arndb.de> > > >> > > >> Calling memcmp() and memchr() with an intentional buffer overflow > > >> is now caught at compile time: > > >> > > >> In function 'memcmp', > > >> inlined from 'kasan_memcmp' at lib/test_kasan.c:897:2: > > >> include/linux/fortify-string.h:263:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > > >> 263 | __read_overflow(); > > >> | ^~~~~~~~~~~~~~~~~ > > >> In function 'memchr', > > >> inlined from 'kasan_memchr' at lib/test_kasan.c:872:2: > > >> include/linux/fortify-string.h:277:17: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter) > > >> 277 | __read_overflow(); > > >> | ^~~~~~~~~~~~~~~~~ > > >> > > >> Change the kasan tests to wrap those inside of a noinline function > > >> to prevent the compiler from noticing the bug and let kasan find > > >> it at runtime. > > >> > > >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > > > > >Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > > > > How about just explicitly making the size invisible to the compiler? > > > > I did this for similar issues in the same source: > > > > https://lore.kernel.org/linux-hardening/20211006181544.1670992-1-keescook@chromium.org/T/#u This is already fixed in your tree with: "kasan: test: consolidate workarounds for unwanted __alloc_size() protection" which was based on this original patch (and my comments).
diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 67ed689a0b1b..903215e944f1 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -852,6 +852,21 @@ static void kmem_cache_invalid_free(struct kunit *test) kmem_cache_destroy(cache); } +/* + * noinline wrappers to prevent the compiler from noticing the overflow + * at compile time rather than having kasan catch it. + * */ +static noinline void *__kasan_memchr(const void *s, int c, size_t n) +{ + return memchr(s, c, n); +} + +static noinline int __kasan_memcmp(const void *s1, const void *s2, size_t n) +{ + return memcmp(s1, s2, n); +} + + static void kasan_memchr(struct kunit *test) { char *ptr; @@ -870,7 +885,7 @@ static void kasan_memchr(struct kunit *test) KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); KUNIT_EXPECT_KASAN_FAIL(test, - kasan_ptr_result = memchr(ptr, '1', size + 1)); + kasan_ptr_result = __kasan_memchr(ptr, '1', size + 1)); kfree(ptr); } @@ -895,7 +910,7 @@ static void kasan_memcmp(struct kunit *test) memset(arr, 0, sizeof(arr)); KUNIT_EXPECT_KASAN_FAIL(test, - kasan_int_result = memcmp(ptr, arr, size+1)); + kasan_int_result = __kasan_memcmp(ptr, arr, size+1)); kfree(ptr); }