linux-kernel - [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug

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Message-ID: <20210623133533.2246-2-yee.lee@mediatek.com>
Date:   Wed, 23 Jun 2021 21:35:32 +0800
From:   <yee.lee@...iatek.com>
To:     <andreyknvl@...il.com>
CC:     <wsd_upstream@...iatek.com>, Yee Lee <yee.lee@...iatek.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "open list:KASAN" <kasan-dev@...glegroups.com>,
        "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
Subject: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug

From: Yee Lee <yee.lee@...iatek.com>

Issue: when SLUB debug is on, hwtag kasan_unpoison() would overwrite the redzone with unaligned object size.

An additional memzero_explicit() path is added to replacing hwtag initialization
at SLUB deubg mode.

Signed-off-by: Yee Lee <yee.lee@...iatek.com>
Suggested-by: Marco Elver <elver@...gle.com>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc: Alexander Potapenko <glider@...gle.com>
Cc: Andrey Konovalov <andreyknvl@...il.com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
---
 mm/kasan/kasan.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index d8faa64614b7..e984a9ac814d 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -387,10 +387,12 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init)
 
 	if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
 		return;
+	#if IS_ENABLED(CONFIG_SLUB_DEBUG)
 	if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
 		init = false;
-		memset((void *)addr, 0, size);
+		memzero_explicit((void *)addr, size);
 	}
+	#endif
 	size = round_up(size, KASAN_GRANULE_SIZE);
 	hw_set_mem_tag_range((void *)addr, size, tag, init);
 }
-- 
2.18.0