linux-kernel - [PATCH mm 12/22] kasan: simplify kasan_find_first_bad

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Message-Id: <a49576f7a23283d786ba61579cb0c5057e8f0b9b.1646237226.git.andreyknvl@google.com>
Date:   Wed,  2 Mar 2022 17:36:32 +0100
From:   andrey.konovalov@...ux.dev
To:     Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH mm 12/22] kasan: simplify kasan_find_first_bad_addr call sites

From: Andrey Konovalov <andreyknvl@...gle.com>

Move the addr_has_metadata() check into kasan_find_first_bad_addr().

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 mm/kasan/report.c         | 5 +----
 mm/kasan/report_generic.c | 4 ++++
 mm/kasan/report_hw_tags.c | 1 +
 mm/kasan/report_sw_tags.c | 4 ++++
 4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index bb4c29b439b1..a0d4a9d3f933 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -444,10 +444,7 @@ static void __kasan_report(void *addr, size_t size, bool is_write,
 	start_report(&flags, true);
 
 	info.access_addr = addr;
-	if (addr_has_metadata(addr))
-		info.first_bad_addr = kasan_find_first_bad_addr(addr, size);
-	else
-		info.first_bad_addr = addr;
+	info.first_bad_addr = kasan_find_first_bad_addr(addr, size);
 	info.access_size = size;
 	info.is_write = is_write;
 	info.ip = ip;
diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c
index 7e03cca569a7..182239ca184c 100644
--- a/mm/kasan/report_generic.c
+++ b/mm/kasan/report_generic.c
@@ -34,8 +34,12 @@ void *kasan_find_first_bad_addr(void *addr, size_t size)
 {
 	void *p = addr;
 
+	if (!addr_has_metadata(p))
+		return p;
+
 	while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
 		p += KASAN_GRANULE_SIZE;
+
 	return p;
 }
 
diff --git a/mm/kasan/report_hw_tags.c b/mm/kasan/report_hw_tags.c
index 5dbbbb930e7a..f3d3be614e4b 100644
--- a/mm/kasan/report_hw_tags.c
+++ b/mm/kasan/report_hw_tags.c
@@ -17,6 +17,7 @@
 
 void *kasan_find_first_bad_addr(void *addr, size_t size)
 {
+	/* Return the same value regardless of whether addr_has_metadata(). */
 	return kasan_reset_tag(addr);
 }
 
diff --git a/mm/kasan/report_sw_tags.c b/mm/kasan/report_sw_tags.c
index 44577b8d47a7..68724ba3d814 100644
--- a/mm/kasan/report_sw_tags.c
+++ b/mm/kasan/report_sw_tags.c
@@ -35,8 +35,12 @@ void *kasan_find_first_bad_addr(void *addr, size_t size)
 	void *p = kasan_reset_tag(addr);
 	void *end = p + size;
 
+	if (!addr_has_metadata(p))
+		return p;
+
 	while (p < end && tag == *(u8 *)kasan_mem_to_shadow(p))
 		p += KASAN_GRANULE_SIZE;
+
 	return p;
 }
 
-- 
2.25.1