Re: [PATCH 4/5] Makefile: Enable -Warray-bounds
From: Guenter Roeck
Date: Wed Feb 02 2022 - 18:33:17 EST
On 2/2/22 12:56, Kees Cook wrote:
On Wed, Feb 02, 2022 at 08:09:03AM -0800, Guenter Roeck wrote:
On Wed, Aug 18, 2021 at 01:11:17AM -0700, Kees Cook wrote:
With the recent fixes for flexible arrays and expanded FORTIFY_SOURCE
coverage, it is now possible to enable -Warray-bounds. Since both
GCC and Clang include -Warray-bounds in -Wall, we just need to stop
disabling it.
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: linux-kbuild@xxxxxxxxxxxxxxx
Co-developed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
Makefile | 1 -
1 file changed, 1 deletion(-)
diff --git a/Makefile b/Makefile
index a4aca01a4835..af22b83cede7 100644
--- a/Makefile
+++ b/Makefile
@@ -1072,7 +1072,6 @@ KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
# We'll want to enable this eventually, but it's not going away for 5.7 at least
KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds)
-KBUILD_CFLAGS += -Wno-array-bounds
KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
# Another good warning that we'll want to enable eventually
alpha:defconfig:
In function '__memset',
inlined from '__bad_pagetable' at arch/alpha/mm/init.c:79:2:
./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds]
37 | return __builtin_memset(s, c, n);
| ^~~~~~~~~~~~~~~~~~~~~~~~~
In function '__memset',
inlined from '__bad_page' at arch/alpha/mm/init.c:86:2:
./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds]
37 | return __builtin_memset(s, c, n);
| ^~~~~~~~~~~~~~~~~~~~~~~~~
In function '__memset',
inlined from 'paging_init' at arch/alpha/mm/init.c:256:2:
./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds]
37 | return __builtin_memset(s, c, n);
Thanks! I'll take a look. Every instance of the "[0, 0]" bounds means
the compiler believes there's a way for the destination to be determined
at compile-time to be NULL.
xtensa:allmodconfig:
--------------
Error log:
In file included from include/linux/uaccess.h:11,
from include/linux/sched/task.h:11,
from arch/xtensa/kernel/process.c:21:
arch/xtensa/kernel/process.c: In function 'copy_thread':
arch/xtensa/kernel/process.c:262:52: error: array subscript 53 is above array bounds of 'long unsigned int[16]'
I assume this is a weird cast. I will also check this one out.
int callinc = (regs->areg[0] >> 30) & 3;
int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
put_user(regs->areg[caller_ars+1],
^^^^^^^^^^^^^^^^^^^^^^^^
(unsigned __user*)(usp - 12));
I think the problem is that XCHAL_NUM_AREGS can be up to 64,
but the size of struct pt_regs->areg[] is fixed to 16.
Guenter