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authorChristian Brauner <christian@brauner.io>2019-01-21 11:48:05 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-01-22 12:25:53 +0100
commit01b3f1fc568352a1ffdcd3ee82a0297f16cc9bd9 (patch)
tree8af8649554d683e76d9f3fd12e5f0d748ee189e6 /drivers/android
parent36975fc3e5f241cc4f45df4ab4624d7d5199d9ed (diff)
binderfs: rework binderfs_binder_device_create()
- switch from d_alloc_name() + d_lookup() to lookup_one_len(): Instead of using d_alloc_name() and then doing a d_lookup() with the allocated dentry to find whether a device with the name we're trying to create already exists switch to using lookup_one_len(). The latter will either return the existing dentry or a new one. - switch from kmalloc() + strscpy() to kmemdup(): Use a more idiomatic way to copy the name for the new dentry that userspace gave us. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Christian Brauner <christian@brauner.io> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/android')
-rw-r--r--drivers/android/binderfs.c39
1 files changed, 19 insertions, 20 deletions
diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
index 89a2ee1a02f6..1e077498a507 100644
--- a/drivers/android/binderfs.c
+++ b/drivers/android/binderfs.c
@@ -11,6 +11,7 @@
#include <linux/kdev_t.h>
#include <linux/kernel.h>
#include <linux/list.h>
+#include <linux/namei.h>
#include <linux/magic.h>
#include <linux/major.h>
#include <linux/miscdevice.h>
@@ -106,7 +107,7 @@ bool is_binderfs_device(const struct inode *inode)
* @userp: buffer to copy information about new device for userspace to
* @req: struct binderfs_device as copied from userspace
*
- * This function allocated a new binder_device and reserves a new minor
+ * This function allocates a new binder_device and reserves a new minor
* number for it.
* Minor numbers are limited and tracked globally in binderfs_minors. The
* function will stash a struct binder_device for the specific binder
@@ -122,10 +123,10 @@ static int binderfs_binder_device_create(struct inode *ref_inode,
struct binderfs_device *req)
{
int minor, ret;
- struct dentry *dentry, *dup, *root;
+ struct dentry *dentry, *root;
struct binder_device *device;
- size_t name_len = BINDERFS_MAX_NAME + 1;
char *name = NULL;
+ size_t name_len;
struct inode *inode = NULL;
struct super_block *sb = ref_inode->i_sb;
struct binderfs_info *info = sb->s_fs_info;
@@ -168,12 +169,13 @@ static int binderfs_binder_device_create(struct inode *ref_inode,
inode->i_uid = info->root_uid;
inode->i_gid = info->root_gid;
- name = kmalloc(name_len, GFP_KERNEL);
+ req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
+ name_len = strlen(req->name);
+ /* Make sure to include terminating NUL byte */
+ name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
if (!name)
goto err;
- strscpy(name, req->name, name_len);
-
device->binderfs_inode = inode;
device->context.binder_context_mgr_uid = INVALID_UID;
device->context.name = name;
@@ -192,24 +194,21 @@ static int binderfs_binder_device_create(struct inode *ref_inode,
root = sb->s_root;
inode_lock(d_inode(root));
- dentry = d_alloc_name(root, name);
- if (!dentry) {
+
+ /* look it up */
+ dentry = lookup_one_len(name, root, name_len);
+ if (IS_ERR(dentry)) {
inode_unlock(d_inode(root));
- ret = -ENOMEM;
+ ret = PTR_ERR(dentry);
goto err;
}
- /* Verify that the name userspace gave us is not already in use. */
- dup = d_lookup(root, &dentry->d_name);
- if (dup) {
- if (d_really_is_positive(dup)) {
- dput(dup);
- dput(dentry);
- inode_unlock(d_inode(root));
- ret = -EEXIST;
- goto err;
- }
- dput(dup);
+ if (d_really_is_positive(dentry)) {
+ /* already exists */
+ dput(dentry);
+ inode_unlock(d_inode(root));
+ ret = -EEXIST;
+ goto err;
}
inode->i_private = device;