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Subject[PATCH v3] of: fix memory leak related to safe_name()
Date
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

changes from v2
Add the kfree that was in Mathieu's original patch

drivers/of/base.c | 30 +++++++++++++++++++++---------
drivers/of/dynamic.c | 2 +-
drivers/of/of_private.h | 3 +++
3 files changed, 25 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 +176,16 @@ 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);
+ kfree(name);
if (rc)
return rc;

@@ -1815,6 +1821,12 @@ 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 +1834,7 @@ 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 +1907,7 @@ 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) \
\
 
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