| Message ID | 0c51a7266ea851797dc9816405fc40d860a48db1.1609871239.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kasan: HW_TAGS tests support and fixes | expand |
On Tue, Jan 5, 2021 at 7:28 PM Andrey Konovalov <andreyknvl@google.com> wrote: > > Since the hardware tag-based KASAN mode might not have a redzone that > comes after an allocated object (when kasan.mode=prod is enabled), the > kasan_bitops_tags() test ends up corrupting the next object in memory. > > Change the test so it always accesses the redzone that lies within the > allocated object's boundaries. > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a > --- > lib/test_kasan.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index b67da7f6e17f..3ea52da52714 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -771,17 +771,17 @@ static void kasan_bitops_tags(struct kunit *test) > > /* This test is specifically crafted for the tag-based mode. */ > if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { > - kunit_info(test, "skipping, CONFIG_KASAN_SW_TAGS required"); > + kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required"); > return; > } > > - /* Allocation size will be rounded to up granule size, which is 16. */ > - bits = kzalloc(sizeof(*bits), GFP_KERNEL); > + /* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */ > + bits = kzalloc(48, GFP_KERNEL); I think it might make sense to call ksize() here to ensure we have these spare bytes.
On Tue, Jan 05, 2021 at 07:27PM +0100, Andrey Konovalov wrote: > Since the hardware tag-based KASAN mode might not have a redzone that > comes after an allocated object (when kasan.mode=prod is enabled), the > kasan_bitops_tags() test ends up corrupting the next object in memory. > > Change the test so it always accesses the redzone that lies within the > allocated object's boundaries. > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a Reviewed-by: Marco Elver <elver@google.com> > --- > lib/test_kasan.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index b67da7f6e17f..3ea52da52714 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -771,17 +771,17 @@ static void kasan_bitops_tags(struct kunit *test) > > /* This test is specifically crafted for the tag-based mode. */ > if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { > - kunit_info(test, "skipping, CONFIG_KASAN_SW_TAGS required"); > + kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required"); > return; > } > > - /* Allocation size will be rounded to up granule size, which is 16. */ > - bits = kzalloc(sizeof(*bits), GFP_KERNEL); > + /* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */ > + bits = kzalloc(48, GFP_KERNEL); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bits); > > - /* Do the accesses past the 16 allocated bytes. */ > - kasan_bitops_modify(test, BITS_PER_LONG, &bits[1]); > - kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, &bits[1]); > + /* Do the accesses past the 48 allocated bytes, but within the redone. */ > + kasan_bitops_modify(test, BITS_PER_LONG, (void *)bits + 48); > + kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, (void *)bits + 48); > > kfree(bits); > } > -- > 2.29.2.729.g45daf8777d-goog >
On Tue, Jan 12, 2021 at 9:30 AM Alexander Potapenko <glider@google.com> wrote: > > On Tue, Jan 5, 2021 at 7:28 PM Andrey Konovalov <andreyknvl@google.com> wrote: > > > > Since the hardware tag-based KASAN mode might not have a redzone that > > comes after an allocated object (when kasan.mode=prod is enabled), the > > kasan_bitops_tags() test ends up corrupting the next object in memory. > > > > Change the test so it always accesses the redzone that lies within the > > allocated object's boundaries. > > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > > Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a > > --- > > lib/test_kasan.c | 12 ++++++------ > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > > index b67da7f6e17f..3ea52da52714 100644 > > --- a/lib/test_kasan.c > > +++ b/lib/test_kasan.c > > @@ -771,17 +771,17 @@ static void kasan_bitops_tags(struct kunit *test) > > > > /* This test is specifically crafted for the tag-based mode. */ > > if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { > > - kunit_info(test, "skipping, CONFIG_KASAN_SW_TAGS required"); > > + kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required"); > > return; > > } > > > > - /* Allocation size will be rounded to up granule size, which is 16. */ > > - bits = kzalloc(sizeof(*bits), GFP_KERNEL); > > + /* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */ > > + bits = kzalloc(48, GFP_KERNEL); > > I think it might make sense to call ksize() here to ensure we have > these spare bytes. Calling ksize() will unpoison the whole object. I think it's OK to make assumptions about KASAN internals in tests. I would actually say that we need more tests that check such internal properties. Thanks!
On Tue, Jan 12, 2021 at 9:07 PM 'Andrey Konovalov' via kasan-dev <kasan-dev@googlegroups.com> wrote: > > On Tue, Jan 12, 2021 at 9:30 AM Alexander Potapenko <glider@google.com> wrote: > > > > On Tue, Jan 5, 2021 at 7:28 PM Andrey Konovalov <andreyknvl@google.com> wrote: > > > > > > Since the hardware tag-based KASAN mode might not have a redzone that > > > comes after an allocated object (when kasan.mode=prod is enabled), the > > > kasan_bitops_tags() test ends up corrupting the next object in memory. > > > > > > Change the test so it always accesses the redzone that lies within the > > > allocated object's boundaries. > > > > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > > > Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a Reviewed-by: Alexander Potapenko <glider@google.com> > > > --- > > > lib/test_kasan.c | 12 ++++++------ > > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > > > index b67da7f6e17f..3ea52da52714 100644 > > > --- a/lib/test_kasan.c > > > +++ b/lib/test_kasan.c > > > @@ -771,17 +771,17 @@ static void kasan_bitops_tags(struct kunit *test) > > > > > > /* This test is specifically crafted for the tag-based mode. */ > > > if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { > > > - kunit_info(test, "skipping, CONFIG_KASAN_SW_TAGS required"); > > > + kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required"); > > > return; > > > } > > > > > > - /* Allocation size will be rounded to up granule size, which is 16. */ > > > - bits = kzalloc(sizeof(*bits), GFP_KERNEL); > > > + /* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */ > > > + bits = kzalloc(48, GFP_KERNEL); > > > > I think it might make sense to call ksize() here to ensure we have > > these spare bytes. > > Calling ksize() will unpoison the whole object. Ah, that's right. > I think it's OK to make assumptions about KASAN internals in tests. I > would actually say that we need more tests that check such internal > properties. Agreed.
diff --git a/lib/test_kasan.c b/lib/test_kasan.c index b67da7f6e17f..3ea52da52714 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -771,17 +771,17 @@ static void kasan_bitops_tags(struct kunit *test) /* This test is specifically crafted for the tag-based mode. */ if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { - kunit_info(test, "skipping, CONFIG_KASAN_SW_TAGS required"); + kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required"); return; } - /* Allocation size will be rounded to up granule size, which is 16. */ - bits = kzalloc(sizeof(*bits), GFP_KERNEL); + /* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */ + bits = kzalloc(48, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bits); - /* Do the accesses past the 16 allocated bytes. */ - kasan_bitops_modify(test, BITS_PER_LONG, &bits[1]); - kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, &bits[1]); + /* Do the accesses past the 48 allocated bytes, but within the redone. */ + kasan_bitops_modify(test, BITS_PER_LONG, (void *)bits + 48); + kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, (void *)bits + 48); kfree(bits); }
Since the hardware tag-based KASAN mode might not have a redzone that comes after an allocated object (when kasan.mode=prod is enabled), the kasan_bitops_tags() test ends up corrupting the next object in memory. Change the test so it always accesses the redzone that lies within the allocated object's boundaries. Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a --- lib/test_kasan.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)