efi: Fix error handling in add_sysfs_runtime_map_entry()

Dan Carpenter · Matt Fleming · commit d67e199611b9 · 2015-05-05T16:20:13.000+01:00
I spotted two (difficult to hit) bugs while reviewing this.

1)  There is a double free bug because we unregister "map_kset" in
    add_sysfs_runtime_map_entry() and also efi_runtime_map_init().
2)  If we fail to allocate "entry" then we should return
    ERR_PTR(-ENOMEM) instead of NULL.

Signed-off-by: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Cc: Dave Young &lt;dyoung@redhat.com&gt;
Cc: Guangyu Sun &lt;guangyu.sun@oracle.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Matt Fleming &lt;matt.fleming@intel.com&gt;
diff --git a/drivers/firmware/efi/runtime-map.c b/drivers/firmware/efi/runtime-map.c
@@ -120,7 +120,8 @@ add_sysfs_runtime_map_entry(struct kobject *kobj, int nr)
 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry) {
 		kset_unregister(map_kset);
-		return entry;
+		map_kset = NULL;
+		return ERR_PTR(-ENOMEM);
 	}
 
 	memcpy(&entry->md, efi_runtime_map + nr * efi_memdesc_size,
@@ -132,6 +133,7 @@ add_sysfs_runtime_map_entry(struct kobject *kobj, int nr)
 	if (ret) {
 		kobject_put(&entry->kobj);
 		kset_unregister(map_kset);
+		map_kset = NULL;
 		return ERR_PTR(ret);
 	}
 
@@ -195,8 +197,6 @@ int __init efi_runtime_map_init(struct kobject *efi_kobj)
 		entry = *(map_entries + j);
 		kobject_put(&entry->kobj);
 	}
-	if (map_kset)
-		kset_unregister(map_kset);
 out:
 	return ret;
 }

Original file line number	Diff line number	Diff line change
`@@ -120,7 +120,8 @@ add_sysfs_runtime_map_entry(struct kobject *kobj, int nr)`
`120`	`120`	`entry = kzalloc(sizeof(*entry), GFP_KERNEL);`
`121`	`121`	`if (!entry) {`
`122`	`122`	`kset_unregister(map_kset);`
`123`		`- return entry;`
	`123`	`+ map_kset = NULL;`
	`124`	`+ return ERR_PTR(-ENOMEM);`
`124`	`125`	`}`
`125`	`126`
`126`	`127`	`memcpy(&entry->md, efi_runtime_map + nr * efi_memdesc_size,`
`@@ -132,6 +133,7 @@ add_sysfs_runtime_map_entry(struct kobject *kobj, int nr)`
`132`	`133`	`if (ret) {`
`133`	`134`	`kobject_put(&entry->kobj);`
`134`	`135`	`kset_unregister(map_kset);`
	`136`	`+ map_kset = NULL;`
`135`	`137`	`return ERR_PTR(ret);`
`136`	`138`	`}`
`137`	`139`
`@@ -195,8 +197,6 @@ int __init efi_runtime_map_init(struct kobject *efi_kobj)`
`195`	`197`	`entry = *(map_entries + j);`
`196`	`198`	`kobject_put(&entry->kobj);`
`197`	`199`	`}`
`198`		`- if (map_kset)`
`199`		`- kset_unregister(map_kset);`
`200`	`200`	`out:`
`201`	`201`	`return ret;`
`202`	`202`	`}`