[PATCHv2] fs: add basic sanity check before accessing the files array

[Sascha Hauer]

On Wed, Jul 28, 2010 at 08:27:50AM +0300, Baruch Siach wrote:
> This patch adds some basic file descriptor sanity checks to the file access
> routines. Check whether the given file descriptor is in the files array range,
> and whether the file entry is valid.

Ok, applied

Sascha

> 
> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> ---
>  fs/fs.c |   34 ++++++++++++++++++++++++++++++++++
>  1 files changed, 34 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/fs.c b/fs/fs.c
> index 8417067..3b5f284 100644
> --- a/fs/fs.c
> +++ b/fs/fs.c
> @@ -229,6 +229,16 @@ static void put_file(FILE *f)
>  	files[f->no].in_use = 0;
>  }
>  
> +static int check_fd(int fd)
> +{
> +	if (fd < 0 || fd >= MAX_FILES || !files[fd].in_use) {
> +		errno = -EBADF;
> +		return errno;
> +	}
> +
> +	return 0;
> +}
> +
>  static struct device_d *get_fs_device_by_path(char **path)
>  {
>  	struct device_d *dev;
> @@ -457,6 +467,9 @@ int ioctl(int fd, int request, void *buf)
>  	struct fs_driver_d *fsdrv;
>  	FILE *f = &files[fd];
>  
> +	if (check_fd(fd))
> +		return errno;
> +
>  	dev = f->dev;
>  
>  	fsdrv = (struct fs_driver_d *)dev->driver->type_data;
> @@ -474,6 +487,9 @@ int read(int fd, void *buf, size_t count)
>  	struct fs_driver_d *fsdrv;
>  	FILE *f = &files[fd];
>  
> +	if (check_fd(fd))
> +		return errno;
> +
>  	dev = f->dev;
>  
>  	fsdrv = (struct fs_driver_d *)dev->driver->type_data;
> @@ -494,6 +510,9 @@ ssize_t write(int fd, const void *buf, size_t count)
>  	struct fs_driver_d *fsdrv;
>  	FILE *f = &files[fd];
>  
> +	if (check_fd(fd))
> +		return errno;
> +
>  	dev = f->dev;
>  
>  	fsdrv = (struct fs_driver_d *)dev->driver->type_data;
> @@ -524,6 +543,9 @@ off_t lseek(int fildes, off_t offset, int whence)
>  	FILE *f = &files[fildes];
>  	off_t pos;
>  
> +	if (check_fd(fildes))
> +		return -1;
> +
>  	errno = 0;
>  
>  	dev = f->dev;
> @@ -567,6 +589,9 @@ int erase(int fd, size_t count, unsigned long offset)
>  	struct fs_driver_d *fsdrv;
>  	FILE *f = &files[fd];
>  
> +	if (check_fd(fd))
> +		return errno;
> +
>  	dev = f->dev;
>  
>  	fsdrv = (struct fs_driver_d *)dev->driver->type_data;
> @@ -589,6 +614,9 @@ int protect(int fd, size_t count, unsigned long offset, int prot)
>  	struct fs_driver_d *fsdrv;
>  	FILE *f = &files[fd];
>  
> +	if (check_fd(fd))
> +		return errno;
> +
>  	dev = f->dev;
>  
>  	fsdrv = (struct fs_driver_d *)dev->driver->type_data;
> @@ -627,6 +655,9 @@ void *memmap(int fd, int flags)
>  	FILE *f = &files[fd];
>  	void *ret = (void *)-1;
>  
> +	if (check_fd(fd))
> +		return ret;
> +
>  	dev = f->dev;
>  
>  	fsdrv = (struct fs_driver_d *)dev->driver->type_data;
> @@ -646,6 +677,9 @@ int close(int fd)
>  	struct fs_driver_d *fsdrv;
>  	FILE *f = &files[fd];
>  
> +	if (check_fd(fd))
> +		return errno;
> +
>  	dev = f->dev;
>  
>  	fsdrv = (struct fs_driver_d *)dev->driver->type_data;
> -- 
> 1.7.1
> 
> 
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