On Mon, Sep 09, 2024 at 09:29:58AM +0800, Feng Tang wrote: > Danilo Krummrich raised issue about krealloc+GFP_ZERO [1], and Vlastimil > suggested to add some test case which can sanity test the kmalloc-redzone > and zeroing by utilizing the kmalloc's 'orig_size' debug feature. > > It covers the grow and shrink case of krealloc() re-using current kmalloc > object, and the case of re-allocating a new bigger object. > > User can add "slub_debug" kernel cmdline parameter to test it. > > [1]. https://lore.kernel.org/lkml/20240812223707.32049-1-dakr@xxxxxxxxxx/ > > Suggested-by: Vlastimil Babka <vbabka@xxxxxxx> > Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx> Reviewed-by: Danilo Krummrich <dakr@xxxxxxxxxx> > --- > lib/slub_kunit.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 46 insertions(+) > > diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c > index 6e3a1e5a7142..03e0089149ad 100644 > --- a/lib/slub_kunit.c > +++ b/lib/slub_kunit.c > @@ -186,6 +186,51 @@ static void test_leak_destroy(struct kunit *test) > KUNIT_EXPECT_EQ(test, 1, slab_errors); > } > > +static void test_krealloc_redzone_zeroing(struct kunit *test) > +{ > + char *p; > + int i; > + > + KUNIT_TEST_REQUIRES(test, __slub_debug_enabled()); > + > + /* Allocate a 64B kmalloc object */ > + p = kzalloc(48, GFP_KERNEL); > + if (unlikely(is_kfence_address(p))) { > + kfree(p); > + return; > + } > + memset(p, 0xff, 48); > + > + kasan_disable_current(); > + OPTIMIZER_HIDE_VAR(p); > + > + /* Test shrink */ > + p = krealloc(p, 40, GFP_KERNEL | __GFP_ZERO); > + for (i = 40; i < 64; i++) > + KUNIT_EXPECT_EQ(test, p[i], SLUB_RED_ACTIVE); > + > + /* Test grow within the same 64B kmalloc object */ > + p = krealloc(p, 56, GFP_KERNEL | __GFP_ZERO); > + for (i = 40; i < 56; i++) > + KUNIT_EXPECT_EQ(test, p[i], 0); > + for (i = 56; i < 64; i++) > + KUNIT_EXPECT_EQ(test, p[i], SLUB_RED_ACTIVE); > + > + /* Test grow with allocating a bigger 128B object */ > + p = krealloc(p, 112, GFP_KERNEL | __GFP_ZERO); > + if (unlikely(is_kfence_address(p))) > + goto exit; > + > + for (i = 56; i < 112; i++) > + KUNIT_EXPECT_EQ(test, p[i], 0); > + for (i = 112; i < 128; i++) > + KUNIT_EXPECT_EQ(test, p[i], SLUB_RED_ACTIVE); > + > +exit: > + kfree(p); > + kasan_enable_current(); > +} > + > static int test_init(struct kunit *test) > { > slab_errors = 0; > @@ -196,6 +241,7 @@ static int test_init(struct kunit *test) > } > > static struct kunit_case test_cases[] = { > + KUNIT_CASE(test_krealloc_redzone_zeroing), > KUNIT_CASE(test_clobber_zone), > > #ifndef CONFIG_KASAN > -- > 2.34.1 >
