| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <paezt3cuux5kwv7dvyuo4rrff2felwzmjunkdpyxqjp3fbnyzn@rcdj4xq6djio>
Date: Mon, 9 Jun 2025 16:14:27 +0300
From: Dafna Hirschfeld <dafna.hirschfeld@...el.com>
To: Jan Hendrik Farr <kernel@...rr.cc>
Cc: kees@...nel.org, nathan@...nel.org, ojeda@...nel.org,
ndesaulniers@...gle.com, morbo@...gle.com, justinstitt@...gle.com,
thorsten.blum@...lux.com, ardb@...nel.org, oliver.sang@...el.com,
gustavoars@...nel.org, kent.overstreet@...ux.dev, arnd@...db.de,
gregkh@...uxfoundation.org, akpm@...ux-foundation.org,
tavianator@...ianator.com, linux-hardening@...r.kernel.org,
llvm@...ts.linux.dev, linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Subject: Re: [PATCH 1/1] Compiler Attributes: disable __counted_by for clang
< 19.1.3
On 29.10.2024 15:00, Jan Hendrik Farr wrote:
>This patch disables __counted_by for clang versions < 19.1.3 because
>of the two issues listed below. It does this by introducing
>CONFIG_CC_HAS_COUNTED_BY.
>
>1. clang < 19.1.2 has a bug that can lead to __bdos returning 0:
>https://github.com/llvm/llvm-project/pull/110497
>
>2. clang < 19.1.3 has a bug that can lead to __bdos being off by 4:
>https://github.com/llvm/llvm-project/pull/112636
>
>Fixes: c8248faf3ca2 ("Compiler Attributes: counted_by: Adjust name and identifier expansion")
>Cc: stable@...r.kernel.org # 6.6.x: 16c31dd7fdf6: Compiler Attributes: counted_by: bump min gcc version
>Cc: stable@...r.kernel.org # 6.6.x: 2993eb7a8d34: Compiler Attributes: counted_by: fixup clang URL
>Cc: stable@...r.kernel.org # 6.6.x: 231dc3f0c936: lkdtm/bugs: Improve warning message for compilers without counted_by support
>Cc: stable@...r.kernel.org # 6.6.x
>Reported-by: Nathan Chancellor <nathan@...nel.org>
>Closes: https://lore.kernel.org/all/20240913164630.GA4091534@thelio-3990X/
>Reported-by: kernel test robot <oliver.sang@...el.com>
>Closes: https://lore.kernel.org/oe-lkp/202409260949.a1254989-oliver.sang@intel.com
>Link: https://lore.kernel.org/all/Zw8iawAF5W2uzGuh@archlinux/T/#m204c09f63c076586a02d194b87dffc7e81b8de7b
>Suggested-by: Nathan Chancellor <nathan@...nel.org>
>Signed-off-by: Jan Hendrik Farr <kernel@...rr.cc>
>Reviewed-by: Nathan Chancellor <nathan@...nel.org>
>Tested-by: Nathan Chancellor <nathan@...nel.org>
>Reviewed-by: Miguel Ojeda <ojeda@...nel.org>
>---
> drivers/misc/lkdtm/bugs.c | 2 +-
> include/linux/compiler_attributes.h | 13 -------------
> include/linux/compiler_types.h | 19 +++++++++++++++++++
> init/Kconfig | 9 +++++++++
> lib/overflow_kunit.c | 2 +-
> 5 files changed, 30 insertions(+), 15 deletions(-)
>
>diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
>index 62ba01525479..376047beea3d 100644
>--- a/drivers/misc/lkdtm/bugs.c
>+++ b/drivers/misc/lkdtm/bugs.c
>@@ -445,7 +445,7 @@ static void lkdtm_FAM_BOUNDS(void)
>
> pr_err("FAIL: survived access of invalid flexible array member index!\n");
>
>- if (!__has_attribute(__counted_by__))
>+ if (!IS_ENABLED(CONFIG_CC_HAS_COUNTED_BY))
> pr_warn("This is expected since this %s was built with a compiler that does not support __counted_by\n",
> lkdtm_kernel_info);
> else if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
>diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
>index 32284cd26d52..c16d4199bf92 100644
>--- a/include/linux/compiler_attributes.h
>+++ b/include/linux/compiler_attributes.h
>@@ -94,19 +94,6 @@
> # define __copy(symbol)
> #endif
>
>-/*
>- * Optional: only supported since gcc >= 15
>- * Optional: only supported since clang >= 18
>- *
>- * gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896
>- * clang: https://github.com/llvm/llvm-project/pull/76348
>- */
>-#if __has_attribute(__counted_by__)
>-# define __counted_by(member) __attribute__((__counted_by__(member)))
>-#else
>-# define __counted_by(member)
>-#endif
>-
Why is the define of __counted_by moved from here (compiler_attributes.h)
to a different location (compiler_types.h) ?
I am asking this because I try to compile an out of tree kernel module with ofed headers.
in the ofed header of compiler_types.h there is an added include of types.h:
#include_next <linux/compiler_attributes.h>
#include <linux/types.h>
so what happen is that __counted_by is defined in types.h, and then I get a compilation error:
././include/linux/compiler_types.h:323: error: "__counted_by" redefined [-Werror]
I am not sure yet how this should be fixed.
Thank you,
Dafna
> /*
> * Optional: not supported by gcc
> * Optional: only supported since clang >= 14.0
>diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
>index 1a957ea2f4fe..639be0f30b45 100644
>--- a/include/linux/compiler_types.h
>+++ b/include/linux/compiler_types.h
>@@ -323,6 +323,25 @@ struct ftrace_likely_data {
> #define __no_sanitize_or_inline __always_inline
> #endif
>
>+/*
>+ * Optional: only supported since gcc >= 15
>+ * Optional: only supported since clang >= 18
>+ *
>+ * gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896
>+ * clang: https://github.com/llvm/llvm-project/pull/76348
>+ *
>+ * __bdos on clang < 19.1.2 can erroneously return 0:
>+ * https://github.com/llvm/llvm-project/pull/110497
>+ *
>+ * __bdos on clang < 19.1.3 can be off by 4:
>+ * https://github.com/llvm/llvm-project/pull/112636
>+ */
>+#ifdef CONFIG_CC_HAS_COUNTED_BY
>+# define __counted_by(member) __attribute__((__counted_by__(member)))
>+#else
>+# define __counted_by(member)
>+#endif
>+
> /*
> * Apply __counted_by() when the Endianness matches to increase test coverage.
> */
>diff --git a/init/Kconfig b/init/Kconfig
>index 530a382ee0fe..92f106cf5572 100644
>--- a/init/Kconfig
>+++ b/init/Kconfig
>@@ -116,6 +116,15 @@ config CC_HAS_ASM_INLINE
> config CC_HAS_NO_PROFILE_FN_ATTR
> def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
>
>+config CC_HAS_COUNTED_BY
>+ # TODO: when gcc 15 is released remove the build test and add
>+ # a gcc version check
>+ def_bool $(success,echo 'struct flex { int count; int array[] __attribute__((__counted_by__(count))); };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror)
>+ # clang needs to be at least 19.1.3 to avoid __bdos miscalculations
>+ # https://github.com/llvm/llvm-project/pull/110497
>+ # https://github.com/llvm/llvm-project/pull/112636
>+ depends on !(CC_IS_CLANG && CLANG_VERSION < 190103)
>+
> config PAHOLE_VERSION
> int
> default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
>diff --git a/lib/overflow_kunit.c b/lib/overflow_kunit.c
>index 2abc78367dd1..5222c6393f11 100644
>--- a/lib/overflow_kunit.c
>+++ b/lib/overflow_kunit.c
>@@ -1187,7 +1187,7 @@ static void DEFINE_FLEX_test(struct kunit *test)
> {
> /* Using _RAW_ on a __counted_by struct will initialize "counter" to zero */
> DEFINE_RAW_FLEX(struct foo, two_but_zero, array, 2);
>-#if __has_attribute(__counted_by__)
>+#ifdef CONFIG_CC_HAS_COUNTED_BY
> int expected_raw_size = sizeof(struct foo);
> #else
> int expected_raw_size = sizeof(struct foo) + 2 * sizeof(s16);
>--
>2.47.0
>
Powered by blists - more mailing lists