* [PATCH] [v2] ubsan: disable unsigned-overflow check for i386
@ 2021-01-12 20:29 Arnd Bergmann
2021-01-12 23:53 ` Kees Cook
2021-01-13 0:05 ` Nathan Chancellor
0 siblings, 2 replies; 3+ messages in thread
From: Arnd Bergmann @ 2021-01-12 20:29 UTC (permalink / raw)
To: Nathan Chancellor, Nick Desaulniers, Kees Cook, Stephen Rothwell,
Andrew Morton
Cc: Arnd Bergmann, Marco Elver, George Popescu, linux-kernel,
clang-built-linux
From: Arnd Bergmann <arnd@arndb.de>
Building ubsan kernels even for compile-testing introduced these
warnings in my randconfig environment:
crypto/blake2b_generic.c:98:13: error: stack frame size of 9636 bytes in function 'blake2b_compress' [-Werror,-Wframe-larger-than=]
static void blake2b_compress(struct blake2b_state *S,
crypto/sha512_generic.c:151:13: error: stack frame size of 1292 bytes in function 'sha512_generic_block_fn' [-Werror,-Wframe-larger-than=]
static void sha512_generic_block_fn(struct sha512_state *sst, u8 const *src,
lib/crypto/curve25519-fiat32.c:312:22: error: stack frame size of 2180 bytes in function 'fe_mul_impl' [-Werror,-Wframe-larger-than=]
static noinline void fe_mul_impl(u32 out[10], const u32 in1[10], const u32 in2[10])
lib/crypto/curve25519-fiat32.c:444:22: error: stack frame size of 1588 bytes in function 'fe_sqr_impl' [-Werror,-Wframe-larger-than=]
static noinline void fe_sqr_impl(u32 out[10], const u32 in1[10])
Further testing showed that this is caused by
-fsanitize=unsigned-integer-overflow, but is isolated to the 32-bit
x86 architecture.
The one in blake2b immediately overflows the 8KB stack area architectures,
so better ensure this never happens by disabling the option for 32-bit
x86.
Fixes: d0a3ac549f38 ("ubsan: enable for all*config builds")
Link: https://lore.kernel.org/lkml/20201230154749.746641-1-arnd@kernel.org/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: only turn it off for i386 as discussed
---
lib/Kconfig.ubsan | 1 +
1 file changed, 1 insertion(+)
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index 8b635fd75fe4..3a0b1c930733 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -123,6 +123,7 @@ config UBSAN_SIGNED_OVERFLOW
config UBSAN_UNSIGNED_OVERFLOW
bool "Perform checking for unsigned arithmetic overflow"
depends on $(cc-option,-fsanitize=unsigned-integer-overflow)
+ depends on !X86_32 # avoid excessive stack usage on x86-32/clang
help
This option enables -fsanitize=unsigned-integer-overflow which checks
for overflow of any arithmetic operations with unsigned integers. This
--
2.29.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] [v2] ubsan: disable unsigned-overflow check for i386
2021-01-12 20:29 [PATCH] [v2] ubsan: disable unsigned-overflow check for i386 Arnd Bergmann
@ 2021-01-12 23:53 ` Kees Cook
2021-01-13 0:05 ` Nathan Chancellor
1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2021-01-12 23:53 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Nathan Chancellor, Nick Desaulniers, Stephen Rothwell,
Andrew Morton, Arnd Bergmann, Marco Elver, George Popescu,
linux-kernel, clang-built-linux
On Tue, Jan 12, 2021 at 09:29:15PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> Building ubsan kernels even for compile-testing introduced these
> warnings in my randconfig environment:
>
> crypto/blake2b_generic.c:98:13: error: stack frame size of 9636 bytes in function 'blake2b_compress' [-Werror,-Wframe-larger-than=]
> static void blake2b_compress(struct blake2b_state *S,
> crypto/sha512_generic.c:151:13: error: stack frame size of 1292 bytes in function 'sha512_generic_block_fn' [-Werror,-Wframe-larger-than=]
> static void sha512_generic_block_fn(struct sha512_state *sst, u8 const *src,
> lib/crypto/curve25519-fiat32.c:312:22: error: stack frame size of 2180 bytes in function 'fe_mul_impl' [-Werror,-Wframe-larger-than=]
> static noinline void fe_mul_impl(u32 out[10], const u32 in1[10], const u32 in2[10])
> lib/crypto/curve25519-fiat32.c:444:22: error: stack frame size of 1588 bytes in function 'fe_sqr_impl' [-Werror,-Wframe-larger-than=]
> static noinline void fe_sqr_impl(u32 out[10], const u32 in1[10])
>
> Further testing showed that this is caused by
> -fsanitize=unsigned-integer-overflow, but is isolated to the 32-bit
> x86 architecture.
>
> The one in blake2b immediately overflows the 8KB stack area architectures,
> so better ensure this never happens by disabling the option for 32-bit
> x86.
>
> Fixes: d0a3ac549f38 ("ubsan: enable for all*config builds")
> Link: https://lore.kernel.org/lkml/20201230154749.746641-1-arnd@kernel.org/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] [v2] ubsan: disable unsigned-overflow check for i386
2021-01-12 20:29 [PATCH] [v2] ubsan: disable unsigned-overflow check for i386 Arnd Bergmann
2021-01-12 23:53 ` Kees Cook
@ 2021-01-13 0:05 ` Nathan Chancellor
1 sibling, 0 replies; 3+ messages in thread
From: Nathan Chancellor @ 2021-01-13 0:05 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Nick Desaulniers, Kees Cook, Stephen Rothwell, Andrew Morton,
Arnd Bergmann, Marco Elver, George Popescu, linux-kernel,
clang-built-linux
On Tue, Jan 12, 2021 at 09:29:15PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> Building ubsan kernels even for compile-testing introduced these
> warnings in my randconfig environment:
>
> crypto/blake2b_generic.c:98:13: error: stack frame size of 9636 bytes in function 'blake2b_compress' [-Werror,-Wframe-larger-than=]
> static void blake2b_compress(struct blake2b_state *S,
> crypto/sha512_generic.c:151:13: error: stack frame size of 1292 bytes in function 'sha512_generic_block_fn' [-Werror,-Wframe-larger-than=]
> static void sha512_generic_block_fn(struct sha512_state *sst, u8 const *src,
> lib/crypto/curve25519-fiat32.c:312:22: error: stack frame size of 2180 bytes in function 'fe_mul_impl' [-Werror,-Wframe-larger-than=]
> static noinline void fe_mul_impl(u32 out[10], const u32 in1[10], const u32 in2[10])
> lib/crypto/curve25519-fiat32.c:444:22: error: stack frame size of 1588 bytes in function 'fe_sqr_impl' [-Werror,-Wframe-larger-than=]
> static noinline void fe_sqr_impl(u32 out[10], const u32 in1[10])
>
> Further testing showed that this is caused by
> -fsanitize=unsigned-integer-overflow, but is isolated to the 32-bit
> x86 architecture.
>
> The one in blake2b immediately overflows the 8KB stack area architectures,
> so better ensure this never happens by disabling the option for 32-bit
> x86.
>
> Fixes: d0a3ac549f38 ("ubsan: enable for all*config builds")
> Link: https://lore.kernel.org/lkml/20201230154749.746641-1-arnd@kernel.org/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> v2: only turn it off for i386 as discussed
> ---
> lib/Kconfig.ubsan | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
> index 8b635fd75fe4..3a0b1c930733 100644
> --- a/lib/Kconfig.ubsan
> +++ b/lib/Kconfig.ubsan
> @@ -123,6 +123,7 @@ config UBSAN_SIGNED_OVERFLOW
> config UBSAN_UNSIGNED_OVERFLOW
> bool "Perform checking for unsigned arithmetic overflow"
> depends on $(cc-option,-fsanitize=unsigned-integer-overflow)
> + depends on !X86_32 # avoid excessive stack usage on x86-32/clang
> help
> This option enables -fsanitize=unsigned-integer-overflow which checks
> for overflow of any arithmetic operations with unsigned integers. This
> --
> 2.29.2
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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