From 2b2cdec98e035b57b0374418fd5e3ba1610c9f10 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 15 Aug 2018 12:14:05 -0700 Subject: [PATCH] isdn: Disable IIOCDBGVAR [ Upstream commit 5e22002aa8809e2efab2da95855f73f63e14a36c ] It was possible to directly leak the kernel address where the isdn_dev structure pointer was stored. This is a kernel ASLR bypass for anyone with access to the ioctl. The code had been present since the beginning of git history, though this shouldn't ever be needed for normal operation, therefore remove it. Reported-by: Al Viro Cc: Karsten Keil Signed-off-by: Kees Cook Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/isdn/i4l/isdn_common.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c index 38a5bb764c7b..598724ffde4e 100644 --- a/drivers/isdn/i4l/isdn_common.c +++ b/drivers/isdn/i4l/isdn_common.c @@ -1640,13 +1640,7 @@ isdn_ioctl(struct file *file, uint cmd, ulong arg) } else return -EINVAL; case IIOCDBGVAR: - if (arg) { - if (copy_to_user(argp, &dev, sizeof(ulong))) - return -EFAULT; - return 0; - } else - return -EINVAL; - break; + return -EINVAL; default: if ((cmd & IIOCDRVCTL) == IIOCDRVCTL) cmd = ((cmd >> _IOC_NRSHIFT) & _IOC_NRMASK) & ISDN_DRVIOCTL_MASK; -- 2.50.1