Messages in this thread | | | From | Arnd Bergmann <> | Date | Thu, 7 Jan 2021 17:09:59 +0100 | Subject | Re: [PATCH] ubsan: disable unsigned-integer-overflow sanitizer with clang |
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On Wed, Jan 6, 2021 at 11:12 PM Arnd Bergmann <arnd@kernel.org> wrote: > > On Wed, Jan 6, 2021 at 10:57 PM Kees Cook <keescook@chromium.org> wrote: > > On Wed, Dec 30, 2020 at 04:47:35PM +0100, Arnd Bergmann wrote: > > > diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan > > > index 8b635fd75fe4..e23873282ba7 100644 > > > --- a/lib/Kconfig.ubsan > > > +++ b/lib/Kconfig.ubsan > > > @@ -122,6 +122,8 @@ config UBSAN_SIGNED_OVERFLOW > > > > > > config UBSAN_UNSIGNED_OVERFLOW > > > bool "Perform checking for unsigned arithmetic overflow" > > > + # clang hugely expands stack usage with -fsanitize=object-size > > > + depends on !CC_IS_CLANG > > > depends on $(cc-option,-fsanitize=unsigned-integer-overflow) > > > > Because of Clang implementation issues (see commit c637693b20da), this is > > already "default n" (and not supported under GCC at all). IIUC, setting > > this to "depends on !COMPILE_TEST" won't work for randconfigs, yes? > > Ah, I had not realized this is clang specific. Adding the !COMPILE_TEST > dependency would hide it for me, which may be good enough for me. > > > Is there some better way to mark this as "known to have issues, please > > don't include in randconfig?" > > > > I'd like to keep it around so people can continue to work out the > > problems with it, but not have unexpecting folks trip over it. ;) > > I've reverted that patch locally now and default-enabled for randconfigs. > Now that I have an otherwise clean build, this should provide me > with a full set of files that produce the warning. If the number is > small enough, I could try opening individual github issues.
A day's worth of randconfig builds with clang-11 or clang-12 shows these instances that exceeded the warning limit:
crypto/blake2b_generic.c:98:13: error: stack frame size of 9636 bytes in function 'blake2b_compress' [-Werror,-Wframe-larger-than=] crypto/sha512_generic.c:151:13: error: stack frame size of 1292 bytes in function 'sha512_generic_block_fn' [-Werror,-Wframe-larger-than=] lib/crypto/curve25519-fiat32.c:312:22: error: stack frame size of 2180 bytes in function 'fe_mul_impl' [-Werror,-Wframe-larger-than=] lib/crypto/curve25519-fiat32.c:444:22: error: stack frame size of 1588 bytes in function 'fe_sqr_impl' [-Werror,-Wframe-larger-than=] fs/btrfs/scrub.c:3028:31: error: stack frame size of 1132 bytes in function 'scrub_stripe' [-Werror,-Wframe-larger-than=] drivers/net/ethernet/intel/e1000/e1000_main.c:3590:6: warning: stack frame size of 1100 bytes in function 'e1000_update_stats' [-Wframe-larger-than=] drivers/net/ethernet/broadcom/tg3.c:11829:13: warning: stack frame size of 1188 bytes in function 'tg3_get_estats' [-Wframe-larger-than=] drivers/net/ethernet/intel/igb/igb_main.c:6551:6: warning: stack frame size of 1348 bytes in function 'igb_update_stats' [-Wframe-larger-than=] drivers/net/ethernet/intel/igc/igc_main.c:3608:6: warning: stack frame size of 1124 bytes in function 'igc_update_stats' [-Wframe-larger-than=] drivers/net/ethernet/qlogic/qed/qed_l2.c:1759:1: warning: stack frame size of 1300 bytes in function '__qed_get_vport_port_stats' [-Wframe-larger-than=] drivers/net/ethernet/intel/ixgbe/ixgbe_main.c:7022:6: warning: stack frame size of 1564 bytes in function 'ixgbe_update_stats' [-Wframe-larger-than=] drivers/net/ethernet/intel/ixgb/ixgb_main.c:1590:1: warning: stack frame size of 1140 bytes in function 'ixgb_update_stats' [-Wframe-larger-than=] drivers/net/ethernet/mellanox/mlx5/core/ipoib/ipoib.c:145:6: warning: stack frame size of 1068 bytes in function 'mlx5i_get_stats' [-Wframe-larger-than=] drivers/staging/media/atomisp/pci/atomisp_cmd.c:5600:5: warning: stack frame size of 1052 bytes in function 'atomisp_set_fmt' [-Wframe-larger-than=]
All of these *only* happen on 32-bit x86, and can be reproduced in a i386_defconfig, with the corresponding drivers (btrfs, sha512, blake2b, curve25519, and the ethernet ones) and UBSAN_UNSIGNED_OVERFLOW manually enabled. Given that few people still care about i386, maybe we could just make the option depend on !CONFIG_X86_32
That config also runs into two more BUILD_BUG_ON() that I had not seen in randconfig tests:
(i386 defconfig plus ubsan) ld.lld: error: undefined symbol: __compiletime_assert_207 >>> referenced by cpu_entry_area.c >>> mm/cpu_entry_area.o:(setup_cpu_entry_area_ptes) in archive arch/x86/built-in.a
(x86-64 defconfig plus ubsan) ld.lld: error: undefined symbol: __compiletime_assert_362 >>> referenced by efi_64.c >>> platform/efi/efi_64.o:(efi_sync_low_kernel_mappings) in archive arch/x86/built-in.a
Arnd
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