Subject: Re: [PATCH] of: fix memory leak related to safe_name()

From: Frank Rowand <[email-masked]>
Date: Wed, 15 Jun 2016 13:34:57 -0700

On 06/15/16 12:12, Rob Herring wrote:
> On Wed, Jun 15, 2016 at 1:13 PM, Frank Rowand <[email-masked]> wrote:
>> From: Frank Rowand <[email-masked]>
>>
>> Fix a memory leak resulting from memory allocation in safe_name().
>> This patch fixes all call sites of safe_name().
>>
>> Mathieu Malaterre reported the memory leak on boot:
>>
>> On my PowerMac device-tree would generate a duplicate name:
>>
>> [    0.023043] device-tree: Duplicate name in PowerPC,G4@0, renamed to "l2-cache#1"
>>
>> in this case a newly allocated name is generated by `safe_name`. However
>> in this case it is never deallocated.
>>
>> The bug was found using kmemleak reported as:
>>
>> unreferenced object 0xdf532e60 (size 32):
>>   comm "swapper", pid 1, jiffies 4294892300 (age 1993.532s)
>>   hex dump (first 32 bytes):
>>     6c 32 2d 63 61 63 68 65 23 31 00 dd e4 dd 1e c2  l2-cache#1......
>>     ec d4 ba ce 04 ec cc de 8e 85 e9 ca c4 ec cc 9e  ................
>>   backtrace:
>>     [<c02d3350>] kvasprintf+0x64/0xc8
>>     [<c02d3400>] kasprintf+0x4c/0x5c
>>     [<c0453814>] safe_name.isra.1+0x80/0xc4
>>     [<c04545d8>] __of_attach_node_sysfs+0x6c/0x11c
>>     [<c075f21c>] of_core_init+0x8c/0xf8
>>     [<c0729594>] kernel_init_freeable+0xd4/0x208
>>     [<c00047e8>] kernel_init+0x24/0x11c
>>     [<c00158ec>] ret_from_kernel_thread+0x5c/0x64
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=120331
>>
>> Signed-off-by: Frank Rowand <[email-masked]>
>> Reported-by: [email-masked]
> 
> [...]
> 
>> Index: b/include/linux/of.h
>> ===================================================================
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -121,6 +121,8 @@ static inline int of_node_is_attached(st
>>  #ifdef CONFIG_OF_DYNAMIC
>>  extern struct device_node *of_node_get(struct device_node *node);
>>  extern void of_node_put(struct device_node *node);
>> +extern void __of_sysfs_remove_bin_file(struct device_node *np,
>> +                                      struct property *prop);
> 
> Should be internal to DT code, right?Yes.

Yes, thanks.  v2 on the way, moved prototype to of_private.h

> 
>>  #else /* CONFIG_OF_DYNAMIC */
>>  /* Dummy ref counting routines - to be implemented later */
>>  static inline struct device_node *of_node_get(struct device_node *node)
>