[PATCH] Fix VFAT_IOCTL_READDIR_BOTH/_SHORT ioctl (2/5)

This fixes the return value of ioctl() for enables using the same way as
readdir().

put/get_user() return code check patch from John R R Leavitt
<jrrl@steampunk.com>

fs/fat/dir.c

@@ -366,7 +366,7 @@ static int fat_readdirx(struct inode *inode, struct file *filp, void *dirent,
 	lock_kernel();
 
 	cpos = filp->f_pos;
-/* Fake . and .. for the root directory. */
+	/* Fake . and .. for the root directory. */
 	if (inode->i_ino == MSDOS_ROOT_INO) {
 		while (cpos < 2) {
 			if (filldir(dirent, "..", cpos+1, cpos, MSDOS_ROOT_INO, DT_DIR) < 0)
@@ -592,23 +592,23 @@ int fat_readdir(struct file *filp, void *dirent, filldir_t filldir)
 	return fat_readdirx(inode, filp, dirent, filldir, 0, 0);
 }
 
-static int vfat_ioctl_fill(
-	void * buf,
-	const char * name,
-	int name_len,
-	loff_t offset,
-	ino_t ino,
-	unsigned int d_type)
+struct fat_ioctl_filldir_callback {
+	struct dirent __user *dirent;
+	int result;
+};
+
+static int fat_ioctl_filldir(void *__buf, const char * name, int name_len,
+			     loff_t offset, ino_t ino, unsigned int d_type)
 {
-	struct dirent *d1 = (struct dirent *)buf;
-	struct dirent *d2 = d1 + 1;
+	struct fat_ioctl_filldir_callback *buf = __buf;
+	struct dirent __user *d1 = buf->dirent;
+	struct dirent __user *d2 = d1 + 1;
 	int len, slen;
 	int dotdir;
 
-	get_user(len, &d1->d_reclen);
-	if (len != 0) {
-		return -1;
-	}
+	if (buf->result)
+		return -EINVAL;
+	buf->result++;
 
 	if ((name_len == 1 && name[0] == '.') ||
 	    (name_len == 2 && name[0] == '.' && name[1] == '.')) {
@@ -619,60 +619,66 @@ static int vfat_ioctl_fill(
 		len = strlen(name);
 	}
 	if (len != name_len) {
-		copy_to_user(d2->d_name, name, len);
-		put_user(0, d2->d_name + len);
-		put_user(len, &d2->d_reclen);
-		put_user(ino, &d2->d_ino);
-		put_user(offset, &d2->d_off);
 		slen = name_len - len;
-		copy_to_user(d1->d_name, name+len+1, slen);
-		put_user(0, d1->d_name+slen);
-		put_user(slen, &d1->d_reclen);
+		if (copy_to_user(d2->d_name, name, len)		||
+		    put_user(0, d2->d_name + len)		||
+		    put_user(len, &d2->d_reclen)		||
+		    put_user(ino, &d2->d_ino)			||
+		    put_user(offset, &d2->d_off)		||
+		    copy_to_user(d1->d_name, name+len+1, slen)	||
+		    put_user(0, d1->d_name+slen)		||
+		    put_user(slen, &d1->d_reclen))
+			goto efault;
 	} else {
-		put_user(0, d2->d_name);
-		put_user(0, &d2->d_reclen);
-		copy_to_user(d1->d_name, name, len);
-		put_user(0, d1->d_name+len);
-		put_user(len, &d1->d_reclen);
+		if (put_user(0, d2->d_name)			||
+		    put_user(0, &d2->d_reclen)			||
+		    copy_to_user(d1->d_name, name, len)		||
+		    put_user(0, d1->d_name+len)			||
+		    put_user(len, &d1->d_reclen))
+			goto efault;
 	}
-
 	return 0;
+efault:
+	buf->result = -EFAULT;
+	return -EFAULT;
 }
 
 int fat_dir_ioctl(struct inode * inode, struct file * filp,
 		  unsigned int cmd, unsigned long arg)
 {
-	int err;
+	struct fat_ioctl_filldir_callback buf;
+	struct dirent __user *d1 = (struct dirent *)arg;
+	int ret, shortname, both;
+
+	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct dirent[2])))
+		return -EFAULT;
 	/*
-	 * We want to provide an interface for Samba to be able
-	 * to get the short filename for a given long filename.
-	 * Samba should use this ioctl instead of readdir() to
-	 * get the information it needs.
+	 * Yes, we don't need this put_user() absolutely. However old
+	 * code didn't return the right value. So, app use this value,
+	 * in order to check whether it is EOF.
 	 */
+	if (put_user(0, &d1->d_reclen))
+		return -EFAULT;
+
+	buf.dirent = d1;
+	buf.result = 0;
 	switch (cmd) {
-	case VFAT_IOCTL_READDIR_BOTH: {
-		struct dirent *d1 = (struct dirent *)arg;
-		err = verify_area(VERIFY_WRITE, d1, sizeof(struct dirent[2]));
-		if (err)
-			return err;
-		put_user(0, &d1->d_reclen);
-		return fat_readdirx(inode,filp,(void *)arg,
-				    vfat_ioctl_fill, 0, 1);
-	}
-	case VFAT_IOCTL_READDIR_SHORT: {
-		struct dirent *d1 = (struct dirent *)arg;
-		put_user(0, &d1->d_reclen);
-		err = verify_area(VERIFY_WRITE, d1, sizeof(struct dirent[2]));
-		if (err)
-			return err;
-		return fat_readdirx(inode,filp,(void *)arg,
-				    vfat_ioctl_fill, 1, 1);
-	}
+	case VFAT_IOCTL_READDIR_SHORT:
+		shortname = 1;
+		both = 1;
+		break;
+	case VFAT_IOCTL_READDIR_BOTH:
+		shortname = 0;
+		both = 1;
+		break;
 	default:
 		return -EINVAL;
 	}
-
-	return 0;
+	ret = fat_readdirx(inode, filp, &buf, fat_ioctl_filldir,
+			   shortname, both);
+	if (ret >= 0)
+		ret = buf.result;
+	return ret;
 }
 
 /***** See if directory is empty */