of: fix memory leak related to safe_name()

PATCH Superseded Frank Rowand 2 participants 3 messages Jun 15, 2016 Device tree

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Frank Rowand

author

2016-06-15 18:13 UTC #0 lore raw

PATCH 1/1 of: fix memory leak related to safe_name()

From: Frank Rowand <[email protected]>

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 protected]>

Reported-by [email protected]

---
 drivers/of/base.c    |   29 ++++++++++++++++++++---------
 drivers/of/dynamic.c |    2 +-
 include/linux/of.h   |    2 ++
 3 files changed, 23 insertions(+), 10 deletions(-)

drivers/of/base.c +20 -9

Index: 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);
 }

drivers/of/dynamic.c +1 -1

Index: 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);
 	}

include/linux/of.h +2 -0

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

Rob Herring

2016-06-15 19:12 UTC #1 lore raw

Quoted 35 lines · Frank Rowand

From: Frank Rowand <[email protected]>
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 protected]>
Reported-by [email protected]

[...]

include/linux/of.h static inline int of_node_is_attached(st · line 125

Quoted 10 lines

Index: b/include/linux/of.h
===================================================================

include/linux/of.h +2 -0

@@ -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?

Quoted 3 lines

include/linux/of.h +0 -0

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

Frank Rowand

author

2016-06-15 20:34 UTC #2 lore raw

Quoted 39 lines · Rob Herring

Quoted 35 lines · Frank Rowand
From: Frank Rowand <[email protected]>
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 protected]>
Reported-by [email protected]
[...]

Quoted 12 lines

include/linux/of.h static inline int of_node_is_attached(st · line 125
Quoted 10 lines
Index: b/include/linux/of.h
===================================================================
include/linux/of.h +2 -0
@@ -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

Quoted 5 lines

Quoted 4 lines

include/linux/of.h +0 -0

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