linux-kernel - [PATCH] mm: prevent KASAN false positives in kmemleak

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Message-Id: <1466617631-68387-1-git-send-email-dvyukov@google.com>
Date:	Wed, 22 Jun 2016 19:47:11 +0200
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	catalin.marinas@....com, linux-mm@...ck.org,
	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, ryabinin.a.a@...il.com,
	kasan-dev@...glegroups.com, glider@...gle.com,
	Dmitry Vyukov <dvyukov@...gle.com>
Subject: [PATCH] mm: prevent KASAN false positives in kmemleak

When kmemleak dumps contents of leaked objects it reads whole
objects regardless of user-requested size. This upsets KASAN.
Disable KASAN checks around object dump.

Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
---
 mm/kmemleak.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index e642992..04320d3 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -307,8 +307,10 @@ static void hex_dump_object(struct seq_file *seq,
 	len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
 
 	seq_printf(seq, "  hex dump (first %zu bytes):\n", len);
+	kasan_disable_current();
 	seq_hex_dump(seq, "    ", DUMP_PREFIX_NONE, HEX_ROW_SIZE,
 		     HEX_GROUP_SIZE, ptr, len, HEX_ASCII);
+	kasan_enable_current();
 }
 
 /*
-- 
2.8.0.rc3.226.g39d4020