[PATCH] kasan: fix conflict with page poisoning

* [PATCH] kasan: fix conflict with page poisoning
@ 2021-03-30 15:35 Andrey Konovalov
  0 siblings, 0 replies; only message in thread
From: Andrey Konovalov @ 2021-03-30 15:35 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Potapenko, Marco Elver, Dmitry Vyukov, Andrey Ryabinin,
	Andrey Konovalov, kasan-dev, linux-mm, linux-kernel,
	Andrey Konovalov

When page poisoning is enabled, it accesses memory that is marked as
poisoned by KASAN, which leas to false-positive KASAN reports.

Suppress the reports by adding KASAN annotations to unpoison_page()
(poison_page() already has them).

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 mm/page_poison.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/page_poison.c b/mm/page_poison.c
index 65cdf844c8ad..655dc5895604 100644
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -77,12 +77,14 @@ static void unpoison_page(struct page *page)
 	void *addr;
 
 	addr = kmap_atomic(page);
+	kasan_disable_current();
 	/*
 	 * Page poisoning when enabled poisons each and every page
 	 * that is freed to buddy. Thus no extra check is done to
 	 * see if a page was poisoned.
 	 */
-	check_poison_mem(addr, PAGE_SIZE);
+	check_poison_mem(kasan_reset_tag(addr), PAGE_SIZE);
+	kasan_enable_current();
 	kunmap_atomic(addr);
 }
 
-- 
2.31.0.291.g576ba9dcdaf-goog



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