> From: Jens Axboe <jens.axboe@oracle.com>
>
> vmsplice_to_user() must always check the user pointer and length
> with access_ok() before copying. Likewise, for the slow path of
> copy_from_user_mmap_sem() we need to check that we may read from
> the user region.
>
> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> Cc: Wojciech Purczynski <cliph@research.coseinc.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> ---
>
> Linus, this fixes a security hole in splice that is now public. I have
> it queued up for the .23 and .24 -stable releases as well.
>
> fs/splice.c | 8 ++++++++
> 1 files changed, 8 insertions(+), 0 deletions(-)
>
> diff --git a/fs/splice.c b/fs/splice.c
> index 4ee49e8..14e2262 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -1179,6 +1179,9 @@ static int copy_from_user_mmap_sem(void *dst, const
> void __user *src, size_t n)
> {
> int partial;
>
> + if (!access_ok(VERIFY_READ, src, n))
> + return -EFAULT;
> +
> pagefault_disable();
> partial = __copy_from_user_inatomic(dst, src, n);
> pagefault_enable();
> @@ -1387,6 +1390,11 @@ static long vmsplice_to_user(struct file *file, const
> struct iovec __user *iov,
> break;
> }
>
> + if (unlikely(!access_ok(VERIFY_WRITE, base, len))) {
> + error = -EFAULT;
> + break;
> + }
> +
> sd.len = 0;
> sd.total_len = len;
> sd.flags = flags;
> --
> 1.5.4.22.g7a20
>
>
> --
> Jens Axboe
> --
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