On Wed, 30 Nov 2011 21:59:59 -0500, Haogang Chen wrote:
> There is a potential integer overflow in nilfs_ioctl_clean_segments().
> When a large argv[n].v_nmembs is passed from the userspace, the
> subsequent call to vmalloc() will allocate a buffer smaller than
> expected, which leads to out-of-bound access in
> nilfs_ioctl_move_blocks() and lfs_clean_segments().
>
> The following check does not prevent the overflow because nsegs is also
> controlled by the userspace and could be very large.
>
> if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
> goto out_free;
>
> This patch clamps argv[n].v_nmembs to UINT_MAX / argv[n].v_size, and
> returns -EINVAL when overflow.
>
> Signed-off-by: Haogang Chen <haogangchen@xxxxxxxxx>
Ahh, that makes sense.
I will apply your patch.
Thanks,
Ryusuke Konishi
> ---
> fs/nilfs2/ioctl.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
> index 41d6743..b805df9 100644
> --- a/fs/nilfs2/ioctl.c
> +++ b/fs/nilfs2/ioctl.c
> @@ -625,6 +625,9 @@ static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
> if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
> goto out_free;
>
> + if (argv[n].v_nmembs >= UINT_MAX / argv[n].v_size)
> + goto out_free;
> +
> len = argv[n].v_size * argv[n].v_nmembs;
> base = (void __user *)(unsigned long)argv[n].v_base;
> if (len == 0) {
> --
> 1.7.5.4
>
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