linux-kernel - [PATCH mm v2 33/33] kasan: better identify bug types for tag-based modes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <355b5734d7f70a70c87ded21b3c4267e1c401b10.1658189199.git.andreyknvl@google.com>
Date:   Tue, 19 Jul 2022 02:10:13 +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 mm v2 33/33] kasan: better identify bug types for tag-based modes

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

Identify the bug type for the tag-based modes based on the stack trace
entries found in the stack ring.

If a free entry is found first (meaning that it was added last), mark the
bug as use-after-free. If an alloc entry is found first, mark the bug as
slab-out-of-bounds. Otherwise, assign the common bug type.

This change returns the functionalify of the previously dropped
CONFIG_KASAN_TAGS_IDENTIFY.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 mm/kasan/report_tags.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c
index 7e267e69ce19..cedcdc5890bc 100644
--- a/mm/kasan/report_tags.c
+++ b/mm/kasan/report_tags.c
@@ -10,7 +10,7 @@
 
 extern struct kasan_stack_ring stack_ring;
 
-static const char *get_bug_type(struct kasan_report_info *info)
+static const char *get_common_bug_type(struct kasan_report_info *info)
 {
 	/*
 	 * If access_size is a negative number, then it has reason to be
@@ -37,9 +37,8 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info)
 	bool is_free;
 	bool alloc_found = false, free_found = false;
 
-	info->bug_type = get_bug_type(info);
-
-	if (!info->cache || !info->object)
+	if (!info->cache || !info->object) {
+		info->bug_type = get_common_bug_type(info);
 		return;
 	}
 
@@ -89,6 +88,13 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info)
 			info->free_track.pid = pid;
 			info->free_track.stack = stack;
 			free_found = true;
+
+			/*
+			 * If a free entry is found first, the bug is likely
+			 * a use-after-free.
+			 */
+			if (!info->bug_type)
+				info->bug_type = "use-after-free";
 		} else {
 			/* Second alloc of the same object. Give up. */
 			if (alloc_found)
@@ -97,8 +103,19 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info)
 			info->alloc_track.pid = pid;
 			info->alloc_track.stack = stack;
 			alloc_found = true;
+
+			/*
+			 * If an alloc entry is found first, the bug is likely
+			 * an out-of-bounds.
+			 */
+			if (!info->bug_type)
+				info->bug_type = "slab-out-of-bounds";
 		}
 	}
 
 	write_unlock_irqrestore(&stack_ring.lock, flags);
+
+	/* Assign the common bug type if no entries were found. */
+	if (!info->bug_type)
+		info->bug_type = get_common_bug_type(info);
 }
-- 
2.25.1