[PATCH] isdn: fix isdn_ioctl memory overrun vulnerability

[PATCH] isdn: fix isdn_ioctl memory overrun vulnerability

Backport of 2.6 commit eafe1aa37e6ec2d56f14732b5240c4dd09f0613a by Karsten Keil

    I4L: fix isdn_ioctl memory overrun vulnerability

    Fix possible memory overrun issue in the isdn ioctl code.

    Found by ADLAB <adlab@venustech.com.cn>

    Signed-off-by: Karsten Keil <kkeil@suse.de>
    Cc: ADLAB <adlab@venustech.com.cn>
    Cc: <stable@kernel.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>