linux-kernel - [PATCH] kasan: Set shadow memory is not memory leaked

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Date:	Sat,  6 Jun 2015 23:10:31 +0900
From:	Masami Ichikawa <masami256@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	Masami Ichikawa <masami256@...il.com>
Subject: [PATCH] kasan: Set shadow memory is not memory leaked

kmemleak reported memory leak in kasan_module_alloc() like following
log, even through kasan_free_shadow() frees that address.

unreferenced object 0xfffffbfff40ac000 (size 118784):
  comm "modprobe", pid 196, jiffies 4294878847 (age 87.590s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff81853a8e>] kmemleak_alloc+0x4e/0xc0
    [<ffffffff812868d0>] __vmalloc_node_range+0x340/0x3f0
    [<ffffffff812b0ae2>] kasan_module_alloc+0x72/0xd0
    [<ffffffff8108c908>] module_alloc+0x78/0xb0
    [<ffffffff81189474>] module_alloc_update_bounds+0x14/0x70
    [<ffffffff8118a457>] load_module+0xf67/0x4670
    [<ffffffff8118dd35>] SyS_init_module+0x1d5/0x220
    [<ffffffff8186642e>] system_call_fastpath+0x12/0x71
    [<ffffffffffffffff>] 0xffffffffffffffff

Kmemleak may think anyone take care of result of __vmalloc_node_range()
after the function.
So, it would be nice to call kmemleak_not_leak() to tell memory is not
leaked.

Signed-off-by: Masami Ichikawa <masami256@...il.com>
---
 mm/kasan/kasan.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 6c513a6..0ef75b9 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -430,6 +430,7 @@ int kasan_module_alloc(void *addr, size_t size)
 			__builtin_return_address(0));
 
 	if (ret) {
+		kmemleak_not_leak(ret);
 		find_vm_area(addr)->flags |= VM_KASAN;
 		return 0;
 	}
-- 
2.4.2

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