linux-kernel - Re: [PATCH] of: fix memory leak related to safe

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Date:	Wed, 15 Jun 2016 14:12:50 -0500
From:	Rob Herring <robh+dt@...nel.org>
To:	Frank Rowand <frowand.list@...il.com>
Cc:	Mathieu Malaterre <mathieu.malaterre@...il.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] of: fix memory leak related to safe_name()

On Wed, Jun 15, 2016 at 1:13 PM, Frank Rowand <frowand.list@...il.com> wrote:
> From: Frank Rowand <frank.rowand@...sony.com>
>
> 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 <frank.rowand@...sony.com>
> Reported-by: mathieu.malaterre@...il.com

[...]

> 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?

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