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SubjectRe: [PATCH v2] of: fix memory leak related to safe_name()
I only tested v2. I confirm this solve the symptoms I was seeing in
the bug report.

Tested-by: Mathieu Malaterre <mathieu.malaterre@gmail.com>

thanks, your patch is actually much cleaner!

On Wed, Jun 15, 2016 at 10:42 PM, Frank Rowand <frowand.list@gmail.com> wrote:
> From: Frank Rowand <frank.rowand@am.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@am.sony.com>
> Reported-by: mathieu.malaterre@gmail.com
> ---
>
> changes from v1
> Move the prototype of __of_sysfs_remove_bin_file() into of_private.h
>
> drivers/of/base.c | 29 ++++++++++++++++++++---------
> drivers/of/dynamic.c | 2 +-
> drivers/of/of_private.h | 3 +++
> 3 files changed, 24 insertions(+), 10 deletions(-)
>
> Index: b/drivers/of/base.c
> ===================================================================
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -112,6 +112,7 @@ static ssize_t of_node_property_read(str
> return memory_read_from_buffer(buf, count, &offset, pp->value, pp->length);
> }
>
> +/* always return newly allocated name, caller must free after use */
> static const char *safe_name(struct kobject *kobj, const char *orig_name)
> {
> const char *name = orig_name;
> @@ -126,9 +127,12 @@ static const char *safe_name(struct kobj
> name = kasprintf(GFP_KERNEL, "%s#%i", orig_name, ++i);
> }
>
> - if (name != orig_name)
> + if (name == orig_name) {
> + name = kstrdup(orig_name, GFP_KERNEL);
> + } else {
> pr_warn("device-tree: Duplicate name in %s, renamed to \"%s\"\n",
> kobject_name(kobj), name);
> + }
> return name;
> }
>
> @@ -159,6 +163,7 @@ int __of_add_property_sysfs(struct devic
> int __of_attach_node_sysfs(struct device_node *np)
> {
> const char *name;
> + struct kobject *parent;
> struct property *pp;
> int rc;
>
> @@ -171,15 +176,15 @@ int __of_attach_node_sysfs(struct device
> np->kobj.kset = of_kset;
> if (!np->parent) {
> /* Nodes without parents are new top level trees */
> - rc = kobject_add(&np->kobj, NULL, "%s",
> - safe_name(&of_kset->kobj, "base"));
> + name = safe_name(&of_kset->kobj, "base");
> + parent = NULL;
> } else {
> name = safe_name(&np->parent->kobj, kbasename(np->full_name));
> - if (!name || !name[0])
> - return -EINVAL;
> -
> - rc = kobject_add(&np->kobj, &np->parent->kobj, "%s", name);
> + parent = &np->parent->kobj;
> }
> + if (!name)
> + return -ENOMEM;
> + rc = kobject_add(&np->kobj, parent, "%s", name);
> if (rc)
> return rc;
>
> @@ -1815,6 +1820,12 @@ int __of_remove_property(struct device_n
> return 0;
> }
>
> +void __of_sysfs_remove_bin_file(struct device_node *np, struct property *prop)
> +{
> + sysfs_remove_bin_file(&np->kobj, &prop->attr);
> + kfree(prop->attr.attr.name);
> +}
> +
> void __of_remove_property_sysfs(struct device_node *np, struct property *prop)
> {
> if (!IS_ENABLED(CONFIG_SYSFS))
> @@ -1822,7 +1833,7 @@ void __of_remove_property_sysfs(struct d
>
> /* at early boot, bail here and defer setup to of_init() */
> if (of_kset && of_node_is_attached(np))
> - sysfs_remove_bin_file(&np->kobj, &prop->attr);
> + __of_sysfs_remove_bin_file(np, prop);
> }
>
> /**
> @@ -1895,7 +1906,7 @@ void __of_update_property_sysfs(struct d
> return;
>
> if (oldprop)
> - sysfs_remove_bin_file(&np->kobj, &oldprop->attr);
> + __of_sysfs_remove_bin_file(np, oldprop);
> __of_add_property_sysfs(np, newprop);
> }
>
> Index: b/drivers/of/dynamic.c
> ===================================================================
> --- a/drivers/of/dynamic.c
> +++ b/drivers/of/dynamic.c
> @@ -55,7 +55,7 @@ void __of_detach_node_sysfs(struct devic
> /* only remove properties if on sysfs */
> if (of_node_is_attached(np)) {
> for_each_property_of_node(np, pp)
> - sysfs_remove_bin_file(&np->kobj, &pp->attr);
> + __of_sysfs_remove_bin_file(np, pp);
> kobject_del(&np->kobj);
> }
>
> Index: b/drivers/of/of_private.h
> ===================================================================
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -83,6 +83,9 @@ extern int __of_attach_node_sysfs(struct
> extern void __of_detach_node(struct device_node *np);
> extern void __of_detach_node_sysfs(struct device_node *np);
>
> +extern void __of_sysfs_remove_bin_file(struct device_node *np,
> + struct property *prop);
> +
> /* iterators for transactions, used for overlays */
> /* forward iterator */
> #define for_each_transaction_entry(_oft, _te) \



--
Mathieu

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