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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,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Borislav Petkov <bp@alien8.de>,
        Dmitry Vyukov <dvyukov@google.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>
Subject: [PATCH 4.9 52/64] x86/uaccess, ubsan: Fix UBSAN vs. SMAP
Date:   Tue, 26 May 2020 20:53:21 +0200
Message-Id: <20200526183930.626243998@linuxfoundation.org>
In-Reply-To: <20200526183913.064413230@linuxfoundation.org>
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From: Peter Zijlstra <peterz@infradead.org>

commit d08965a27e84ca090b504844d50c24fc98587b11 upstream.

UBSAN can insert extra code in random locations; including AC=1
sections. Typically this code is not safe and needs wrapping.

So far, only __ubsan_handle_type_mismatch* have been observed in AC=1
sections and therefore only those are annotated.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[stable backport: only take the lib/Makefile change to resolve gcc-10
 build issues]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 lib/Makefile |    1 +
 1 file changed, 1 insertion(+)

--- a/lib/Makefile
+++ b/lib/Makefile
@@ -230,5 +230,6 @@ obj-$(CONFIG_UCS2_STRING) += ucs2_string
 obj-$(CONFIG_UBSAN) += ubsan.o
 
 UBSAN_SANITIZE_ubsan.o := n
+CFLAGS_ubsan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 
 obj-$(CONFIG_SBITMAP) += sbitmap.o