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Date:   Thu, 10 Sep 2020 14:48:02 +0100
Message-Id: <20200910134802.3160311-1-lenaptr@google.com>
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Subject: [PATCH] sched.h: drop in_ubsan field when UBSAN is in trap mode
From:   Elena Petrova <lenaptr@google.com>
To:     kernel-hardening@lists.openwall.com
Cc:     Elena Petrova <lenaptr@google.com>, linux-kernel@vger.kernel.org,
        Kees Cook <keescook@chromium.org>
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Sender: linux-kernel-owner@vger.kernel.org
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in_ubsan field of task_struct is only used in lib/ubsan.c, which in its
turn is used only `ifneq ($(CONFIG_UBSAN_TRAP),y)`.

Removing unnecessary field from a task_struct will help preserve the
ABI between vanilla and CONFIG_UBSAN_TRAP'ed kernels. In particular,
this will help enabling bounds sanitizer transparently for Android's
GKI.

Signed-off-by: Elena Petrova <lenaptr@google.com>
---
 include/linux/sched.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index afe01e232935..5c7b8dec236e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1008,7 +1008,7 @@ struct task_struct {
 	struct held_lock		held_locks[MAX_LOCK_DEPTH];
 #endif
 
-#ifdef CONFIG_UBSAN
+#if defined(CONFIG_UBSAN) && !defined(CONFIG_UBSAN_TRAP)
 	unsigned int			in_ubsan;
 #endif
 
-- 
2.28.0.526.ge36021eeef-goog