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From:   andrey.konovalov@linux.dev
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Andrey Konovalov <andreyknvl@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Marco Elver <elver@google.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        kasan-dev@googlegroups.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH mm] kasan: print virtual mapping info in reports
Date:   Tue, 22 Feb 2022 17:42:44 +0100
Message-Id: <6ebb11210ae21253198e264d4bb0752c1fad67d7.1645548053.git.andreyknvl@google.com>
MIME-Version: 1.0
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From: Andrey Konovalov <andreyknvl@google.com>

Print virtual mapping range and its creator in reports affecting virtual
mappings.

Also get physical page pointer for such mappings, so page information
gets printed as well.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

---

Note: no need to merge this patch into any of the KASAN vmalloc patches
that are already in mm, better to keep it separate.

Changes v1->v2:
- Add find_vm_area() return value NULL check as suggested by Mark Rutland.
---
 mm/kasan/report.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 137c2c0b09db..f64352008bb8 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -260,8 +260,21 @@ static void print_address_description(void *addr, u8 tag)
 		pr_err(" %pS\n", addr);
 	}
 
+	if (is_vmalloc_addr(addr)) {
+		struct vm_struct *va = find_vm_area(addr);
+
+		if (va) {
+			pr_err("The buggy address belongs to the virtual mapping at\n"
+			       " [%px, %px) created by:\n"
+			       " %pS\n",
+			       va->addr, va->addr + va->size, va->caller);
+
+			page = vmalloc_to_page(page);
+		}
+	}
+
 	if (page) {
-		pr_err("The buggy address belongs to the page:\n");
+		pr_err("The buggy address belongs to the physical page:\n");
 		dump_page(page, "kasan: bad access detected");
 	}
 
-- 
2.25.1