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* [merged] ubsan-disable-unsigned-overflow-check-for-i386.patch removed from -mm tree
@ 2021-01-25 21:35 akpm
  0 siblings, 0 replies; only message in thread
From: akpm @ 2021-01-25 21:35 UTC (permalink / raw)
  To: arnd, elver, georgepope, keescook, mm-commits, natechancellor,
	ndesaulniers, sfr

The patch titled
     Subject: ubsan: disable unsigned-overflow check for i386
has been removed from the -mm tree.  Its filename was

This patch was dropped because it was merged into mainline or a subsystem tree

From: Arnd Bergmann <>
Subject: ubsan: disable unsigned-overflow check for i386

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

The one in blake2b immediately overflows the 8KB stack area architectures,
so better ensure this never happens by disabling the option for 32-bit

Fixes: d0a3ac549f38 ("ubsan: enable for all*config builds")
Signed-off-by: Arnd Bergmann <>
Acked-by: Kees Cook <>
Reviewed-by: Nathan Chancellor <>
Cc: Nick Desaulniers <>
Cc: Stephen Rothwell <>
Cc: Marco Elver <>
Cc: George Popescu <>
Signed-off-by: Andrew Morton <>

 lib/Kconfig.ubsan |    1 +
 1 file changed, 1 insertion(+)

--- a/lib/Kconfig.ubsan~ubsan-disable-unsigned-overflow-check-for-i386
+++ a/lib/Kconfig.ubsan
@@ -123,6 +123,7 @@ config UBSAN_SIGNED_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
 	  This option enables -fsanitize=unsigned-integer-overflow which checks
 	  for overflow of any arithmetic operations with unsigned integers. This

Patches currently in -mm which might be from are

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2021-01-25 21:35 [merged] ubsan-disable-unsigned-overflow-check-for-i386.patch removed from -mm tree akpm

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