kasan: remove kasan_find_vm_area() to prevent possible deadlock

commit 6ee9b3d84775944fb8c8a447961cd01274ac671c upstream.

find_vm_area() couldn't be called in atomic_context.  If find_vm_area() is
called to reports vm area information, kasan can trigger deadlock like:

CPU0                                CPU1
vmalloc();
 alloc_vmap_area();
  spin_lock(&vn->busy.lock)
                                    spin_lock_bh(&some_lock);
   <interrupt occurs>
   <in softirq>
   spin_lock(&some_lock);
                                    <access invalid address>
                                    kasan_report();
                                     print_report();
                                      print_address_description();
                                       kasan_find_vm_area();
                                        find_vm_area();
                                         spin_lock(&vn->busy.lock) // deadlock!

To prevent possible deadlock while kasan reports, remove kasan_find_vm_area().

Link: https://lkml.kernel.org/r/[email protected]
Fixes: c056a36 ("kasan: print virtual mapping info in reports")
Signed-off-by: Yeoreum Yun <[email protected]>
Reported-by: Yunseong Kim <[email protected]>
Reviewed-by: Andrey Ryabinin <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Byungchul Park <[email protected]>
Cc: Dmitriy Vyukov <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Vincenzo Frascino <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: LeviYeoReum

mm/kasan/report.c

@@ -337,17 +337,8 @@ static void print_address_description(void *addr, u8 tag,
 	}
 
 	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);
-			pr_err("\n");
-
-			page = vmalloc_to_page(addr);
-		}
+		pr_err("The buggy address %px belongs to a vmalloc virtual mapping\n", addr);
+		page = vmalloc_to_page(addr);
 	}
 
 	if (page) {