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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Randy Dunlap <rdunlap@infradead.org>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Elena Petrova <lenaptr@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.7 082/376] ubsan: entirely disable alignment checks under UBSAN_TRAP
Date:   Fri, 19 Jun 2020 16:30:00 +0200
Message-Id: <20200619141714.225619751@linuxfoundation.org>
In-Reply-To: <20200619141710.350494719@linuxfoundation.org>
References: <20200619141710.350494719@linuxfoundation.org>
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From: Kees Cook <keescook@chromium.org>

[ Upstream commit 9380ce246a052a1e00121cd480028b6907aeae38 ]

Commit 8d58f222e85f ("ubsan: disable UBSAN_ALIGNMENT under
COMPILE_TEST") tried to fix the pathological results of UBSAN_ALIGNMENT
with UBSAN_TRAP (which objtool would rightly scream about), but it made
an assumption about how COMPILE_TEST gets set (it is not set for
randconfig).  As a result, we need a bigger hammer here: just don't
allow the alignment checks with the trap mode.

Fixes: 8d58f222e85f ("ubsan: disable UBSAN_ALIGNMENT under COMPILE_TEST")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Elena Petrova <lenaptr@google.com>
Link: http://lkml.kernel.org/r/202005291236.000FCB6@keescook
Link: https://lore.kernel.org/lkml/742521db-1e8c-0d7a-1ed4-a908894fb497@infradead.org/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 lib/Kconfig.ubsan | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index 929211039bac..27bcc2568c95 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -63,7 +63,7 @@ config UBSAN_SANITIZE_ALL
 config UBSAN_ALIGNMENT
 	bool "Enable checks for pointers alignment"
 	default !HAVE_EFFICIENT_UNALIGNED_ACCESS
-	depends on !X86 || !COMPILE_TEST
+	depends on !UBSAN_TRAP
 	help
 	  This option enables the check of unaligned memory accesses.
 	  Enabling this option on architectures that support unaligned
-- 
2.25.1