linux-kernel - [PATCH 21/32] kasan: simplify invalid-free reporting

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Message-Id: <f7f5cfc5eb8f1a1f849665641b9dd2cfb4a62c3c.1655150842.git.andreyknvl@google.com>
Date:   Mon, 13 Jun 2022 22:14:12 +0200
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, Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Florian Mayer <fmayer@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 21/32] kasan: simplify invalid-free reporting

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

Right now, KASAN uses the kasan_report_type enum to describe report types.

As this enum only has two options, replace it with a bool variable.

Also, unify printing report header for invalid-free and other bug types
in print_error_description().

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 mm/kasan/kasan.h  |  7 +------
 mm/kasan/report.c | 16 +++++++---------
 2 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index e8329935fbfb..f696d50b09fb 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -146,16 +146,11 @@ static inline bool kasan_requires_meta(void)
 #define META_MEM_BYTES_PER_ROW (META_BYTES_PER_ROW * KASAN_GRANULE_SIZE)
 #define META_ROWS_AROUND_ADDR 2
 
-enum kasan_report_type {
-	KASAN_REPORT_ACCESS,
-	KASAN_REPORT_INVALID_FREE,
-};
-
 struct kasan_report_info {
-	enum kasan_report_type type;
 	void *access_addr;
 	void *first_bad_addr;
 	size_t access_size;
+	bool is_free;
 	bool is_write;
 	unsigned long ip;
 };
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index f951fd39db74..7269b6249488 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -175,14 +175,12 @@ static void end_report(unsigned long *flags, void *addr)
 
 static void print_error_description(struct kasan_report_info *info)
 {
-	if (info->type == KASAN_REPORT_INVALID_FREE) {
-		pr_err("BUG: KASAN: double-free or invalid-free in %pS\n",
-		       (void *)info->ip);
-		return;
-	}
+	const char *bug_type = info->is_free ?
+		"double-free or invalid-free" : kasan_get_bug_type(info);
 
-	pr_err("BUG: KASAN: %s in %pS\n",
-		kasan_get_bug_type(info), (void *)info->ip);
+	pr_err("BUG: KASAN: %s in %pS\n", bug_type, (void *)info->ip);
+	if (info->is_free)
+		return;
 	if (info->access_size)
 		pr_err("%s of size %zu at addr %px by task %s/%d\n",
 			info->is_write ? "Write" : "Read", info->access_size,
@@ -435,11 +433,11 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip)
 
 	start_report(&flags, true);
 
-	info.type = KASAN_REPORT_INVALID_FREE;
 	info.access_addr = ptr;
 	info.first_bad_addr = kasan_reset_tag(ptr);
 	info.access_size = 0;
 	info.is_write = false;
+	info.is_free = true;
 	info.ip = ip;
 
 	print_report(&info);
@@ -468,11 +466,11 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
 
 	start_report(&irq_flags, true);
 
-	info.type = KASAN_REPORT_ACCESS;
 	info.access_addr = ptr;
 	info.first_bad_addr = kasan_find_first_bad_addr(ptr, size);
 	info.access_size = size;
 	info.is_write = is_write;
+	info.is_free = false;
 	info.ip = ip;
 
 	print_report(&info);
-- 
2.25.1