From b40ef8696fbbb1107fbe5f4afc21c357f16e5ffc Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 14 Dec 2015 18:44:44 -0500
Subject: saner calling conventions for copy_mount_options()

let it just return NULL, pointer to kernel copy or ERR_PTR().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/compat.c    | 21 ++++++++++-----------
 fs/internal.h  |  2 +-
 fs/namespace.c | 35 +++++++++++++++++------------------
 3 files changed, 28 insertions(+), 30 deletions(-)

(limited to 'fs')

diff --git a/fs/compat.c b/fs/compat.c
index 6fd272d455e4..a71936a3f4cb 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -792,7 +792,7 @@ COMPAT_SYSCALL_DEFINE5(mount, const char __user *, dev_name,
 		       const void __user *, data)
 {
 	char *kernel_type;
-	unsigned long data_page;
+	void *options;
 	char *kernel_dev;
 	int retval;
 
@@ -806,26 +806,25 @@ COMPAT_SYSCALL_DEFINE5(mount, const char __user *, dev_name,
 	if (IS_ERR(kernel_dev))
 		goto out1;
 
-	retval = copy_mount_options(data, &data_page);
-	if (retval < 0)
+	options = copy_mount_options(data);
+	retval = PTR_ERR(options);
+	if (IS_ERR(options))
 		goto out2;
 
-	retval = -EINVAL;
-
-	if (kernel_type && data_page) {
+	if (kernel_type && options) {
 		if (!strcmp(kernel_type, NCPFS_NAME)) {
-			do_ncp_super_data_conv((void *)data_page);
+			do_ncp_super_data_conv(options);
 		} else if (!strcmp(kernel_type, NFS4_NAME)) {
-			if (do_nfs4_super_data_conv((void *) data_page))
+			retval = -EINVAL;
+			if (do_nfs4_super_data_conv(options))
 				goto out3;
 		}
 	}
 
-	retval = do_mount(kernel_dev, dir_name, kernel_type,
-			flags, (void*)data_page);
+	retval = do_mount(kernel_dev, dir_name, kernel_type, flags, options);
 
  out3:
-	free_page(data_page);
+	kfree(options);
  out2:
 	kfree(kernel_dev);
  out1:
diff --git a/fs/internal.h b/fs/internal.h
index 71859c4d0b41..aa81316aaf47 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -55,7 +55,7 @@ extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
 /*
  * namespace.c
  */
-extern int copy_mount_options(const void __user *, unsigned long *);
+extern void *copy_mount_options(const void __user *);
 extern char *copy_mount_string(const void __user *);
 
 extern struct vfsmount *lookup_mnt(struct path *);
diff --git a/fs/namespace.c b/fs/namespace.c
index b27156f2e68b..33a75c8e9fcb 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2601,18 +2601,18 @@ static long exact_copy_from_user(void *to, const void __user * from,
 	return n;
 }
 
-int copy_mount_options(const void __user * data, unsigned long *where)
+void *copy_mount_options(const void __user * data)
 {
 	int i;
-	unsigned long page;
 	unsigned long size;
+	char *copy;
 
-	*where = 0;
 	if (!data)
-		return 0;
+		return NULL;
 
-	if (!(page = __get_free_page(GFP_KERNEL)))
-		return -ENOMEM;
+	copy = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!copy)
+		return ERR_PTR(-ENOMEM);
 
 	/* We only care that *some* data at the address the user
 	 * gave us is valid.  Just in case, we'll zero
@@ -2623,15 +2623,14 @@ int copy_mount_options(const void __user * data, unsigned long *where)
 	if (size > PAGE_SIZE)
 		size = PAGE_SIZE;
 
-	i = size - exact_copy_from_user((void *)page, data, size);
+	i = size - exact_copy_from_user(copy, data, size);
 	if (!i) {
-		free_page(page);
-		return -EFAULT;
+		kfree(copy);
+		return ERR_PTR(-EFAULT);
 	}
 	if (i != PAGE_SIZE)
-		memset((char *)page + i, 0, PAGE_SIZE - i);
-	*where = page;
-	return 0;
+		memset(copy + i, 0, PAGE_SIZE - i);
+	return copy;
 }
 
 char *copy_mount_string(const void __user *data)
@@ -2896,7 +2895,7 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
 	int ret;
 	char *kernel_type;
 	char *kernel_dev;
-	unsigned long data_page;
+	void *options;
 
 	kernel_type = copy_mount_string(type);
 	ret = PTR_ERR(kernel_type);
@@ -2908,14 +2907,14 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
 	if (IS_ERR(kernel_dev))
 		goto out_dev;
 
-	ret = copy_mount_options(data, &data_page);
-	if (ret < 0)
+	options = copy_mount_options(data);
+	ret = PTR_ERR(options);
+	if (IS_ERR(options))
 		goto out_data;
 
-	ret = do_mount(kernel_dev, dir_name, kernel_type, flags,
-		(void *) data_page);
+	ret = do_mount(kernel_dev, dir_name, kernel_type, flags, options);
 
-	free_page(data_page);
+	kfree(options);
 out_data:
 	kfree(kernel_dev);
 out_dev:
-- 
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