fs: namespace: suppress 'may be used uninitialized' warnings

commit b8850d1fa8e2f6653e57daf6d08e58c5f5eb2c85 upstream.

The gcc version 4.9.1 compiler complains Even though it isn't possible for
these variables to not get initialized before they are used.

fs/namespace.c: In function ‘SyS_mount’:
fs/namespace.c:2720:8: warning: ‘kernel_dev’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  ret = do_mount(kernel_dev, kernel_dir->name, kernel_type, flags,
        ^
fs/namespace.c:2699:8: note: ‘kernel_dev’ was declared here
  char *kernel_dev;
        ^
fs/namespace.c:2720:8: warning: ‘kernel_type’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  ret = do_mount(kernel_dev, kernel_dir->name, kernel_type, flags,
        ^
fs/namespace.c:2697:8: note: ‘kernel_type’ was declared here
  char *kernel_type;
        ^

Fix the warnings by simplifying copy_mount_string() as suggested by Al Viro.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[sw0312.kim: Backport from mainline to fix build warning]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: Id8e784ebc6e4300aebd883d9766fd66cb8ab76c1

diff --git a/fs/compat.c b/fs/compat.c
index fc3b55d..0f8a010 100644 (file)
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -781,8 +781,9 @@ asmlinkage long compat_sys_mount(const char __user * dev_name,
        struct filename *dir;
        int retval;
 
-       retval = copy_mount_string(type, &kernel_type);
-       if (retval < 0)
+       kernel_type = copy_mount_string(type);
+       retval = PTR_ERR(kernel_type);
+       if (IS_ERR(kernel_type))
                goto out;
 
        dir = getname(dir_name);
@@ -790,8 +791,9 @@ asmlinkage long compat_sys_mount(const char __user * dev_name,
        if (IS_ERR(dir))
                goto out1;
 
-       retval = copy_mount_string(dev_name, &kernel_dev);
-       if (retval < 0)
+       kernel_dev = copy_mount_string(dev_name);
+       retval = PTR_ERR(kernel_dev);
+       if (IS_ERR(kernel_dev))
                goto out2;
 
        retval = copy_mount_options(data, &data_page);

diff --git a/fs/internal.h b/fs/internal.h
index 2ffa65a..ce2c641 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -50,7 +50,7 @@ extern int __inode_permission(struct inode *, int);
  * namespace.c
  */
 extern int copy_mount_options(const void __user *, unsigned long *);
-extern int copy_mount_string(const void __user *, char **);
+extern char *copy_mount_string(const void __user *);
 
 extern struct vfsmount *lookup_mnt(struct path *);
 extern int finish_automount(struct vfsmount *, struct path *);

diff --git a/fs/namespace.c b/fs/namespace.c
index cc66a86..286cc73 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2283,21 +2283,9 @@ int copy_mount_options(const void __user * data, unsigned long *where)
        return 0;
 }
 
-int copy_mount_string(const void __user *data, char **where)
+char *copy_mount_string(const void __user *data)
 {
-       char *tmp;
-
-       if (!data) {
-               *where = NULL;
-               return 0;
-       }
-
-       tmp = strndup_user(data, PAGE_SIZE);
-       if (IS_ERR(tmp))
-               return PTR_ERR(tmp);
-
-       *where = tmp;
-       return 0;
+       return data ? strndup_user(data, PAGE_SIZE) : NULL;
 }
 
 /*
@@ -2573,8 +2561,9 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
        char *kernel_dev;
        unsigned long data_page;
 
-       ret = copy_mount_string(type, &kernel_type);
-       if (ret < 0)
+       kernel_type = copy_mount_string(type);
+       ret = PTR_ERR(kernel_type);
+       if (IS_ERR(kernel_type))
                goto out_type;
 
        kernel_dir = getname(dir_name);
@@ -2583,8 +2572,9 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
                goto out_dir;
        }
 
-       ret = copy_mount_string(dev_name, &kernel_dev);
-       if (ret < 0)
+       kernel_dev = copy_mount_string(dev_name);
+       ret = PTR_ERR(kernel_dev);
+       if (IS_ERR(kernel_dev))
                goto out_dev;
 
        ret = copy_mount_options(data, &data_page);