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isdn: Disable IIOCDBGVAR 

[ Upstream commit 5e22002aa8 ]

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 <viro@zeniv.linux.org.uk>
Cc: Karsten Keil <isdn@linux-pingi.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Kees Cook 2018-08-15 12:14:05 -07:00 committed by Greg Kroah-Hartman
parent f276e2efb6
commit 2b2cdec98e
1 changed files with 1 additions and 7 deletions
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8
drivers/isdn/i4l/isdn_common.c
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@ -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;