linux-kernel - [PATCH v2] s390: disable -Warray-bounds

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220425121742.3222133-1-svens@linux.ibm.com>
Date:   Mon, 25 Apr 2022 14:17:42 +0200
From:   Sven Schnelle <svens@...ux.ibm.com>
To:     Heiko Carstens <hca@...ux.ibm.com>
Cc:     Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] s390: disable -Warray-bounds

gcc-12 shows a lot of array bound warnings on s390. This is caused
by our S390_lowcore macro:

which uses an hardcoded address of 0. Wrapping that with
absolute_pointer() works, but gcc no longer knows that a 12 bit
instruction is sufficient to access lowcore. So it emits instructions
like 'lghi %r1,0; l %rx,xxx(%r1)' instead of a single load/store
instruction. As s390 stores variables often read/written in lowcore,
this is considered problematic. Therefore disable -Warray-bounds on
s390 when gcc-12 is used until there is a better real solution.

Signed-off-by: Sven Schnelle <svens@...ux.ibm.com>
---
Changes in v2:
- only remove -Warray-bounds for gcc-12

 arch/s390/Makefile | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index e441b60b1812..df325eacf62d 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -30,6 +30,16 @@ KBUILD_CFLAGS_DECOMPRESSOR += -fno-stack-protector
 KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, address-of-packed-member)
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),-g)
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO_DWARF4), $(call cc-option, -gdwarf-4,))
+
+ifdef CONFIG_CC_IS_GCC
+	ifeq ($(call cc-ifversion, -ge, 1200, y), y)
+		ifeq ($(call cc-ifversion, -lt, 1300, y), y)
+			KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds)
+			KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, array-bounds)
+		endif
+	endif
+endif
+
 UTS_MACHINE	:= s390x
 STACK_SIZE	:= $(if $(CONFIG_KASAN),65536,16384)
 CHECKFLAGS	+= -D__s390__ -D__s390x__
-- 
2.35.1