| Message ID | 20240212111609.869266-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | kasan/test: avoid gcc warning for intentional overflow | expand |
On Mon, Feb 12, 2024 at 12:16 PM Arnd Bergmann <arnd@kernel.org> wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > The out-of-bounds test allocates an object that is three bytes too > short in order to validate the bounds checking. Starting with gcc-14, > this causes a compile-time warning as gcc has grown smart enough to > understand the sizeof() logic: > > mm/kasan/kasan_test.c: In function 'kmalloc_oob_16': > mm/kasan/kasan_test.c:443:14: error: allocation of insufficient size '13' for type 'struct <anonymous>' with size '16' [-Werror=alloc-size] > 443 | ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL); > | ^ > > Hide the actual computation behind a RELOC_HIDE() that ensures > the compiler misses the intentional bug. > > Fixes: 3f15801cdc23 ("lib: add kasan test module") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > mm/kasan/kasan_test.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c > index 318d9cec111a..2d8ae4fbe63b 100644 > --- a/mm/kasan/kasan_test.c > +++ b/mm/kasan/kasan_test.c > @@ -440,7 +440,8 @@ static void kmalloc_oob_16(struct kunit *test) > /* This test is specifically crafted for the generic mode. */ > KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); > > - ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL); > + /* RELOC_HIDE to prevent gcc from warning about short alloc */ > + ptr1 = RELOC_HIDE(kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL), 0); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1); > > ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL); > -- > 2.39.2 > Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c index 318d9cec111a..2d8ae4fbe63b 100644 --- a/mm/kasan/kasan_test.c +++ b/mm/kasan/kasan_test.c @@ -440,7 +440,8 @@ static void kmalloc_oob_16(struct kunit *test) /* This test is specifically crafted for the generic mode. */ KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); - ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL); + /* RELOC_HIDE to prevent gcc from warning about short alloc */ + ptr1 = RELOC_HIDE(kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL), 0); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1); ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL);