oss-sec mailing list archives
Re: CVE-2018-1000204: Linux kernel 3.18 to 4.16 infoleak due to incorrect handling of SG_IO ioctl
From: Vladis Dronov <vdronov () redhat com>
Date: Fri, 22 Jun 2018 09:32:43 -0400 (EDT)
Hello, Alexander, Could you please, explain, why do you think CVE-2018-1000204 is a security flaw?
The problem has limited scope, as users don't usually have permissions to access SCSI devices. On the other hand, e.g. the Nero user manual suggests doing `chmod o+r+w /dev/sg*` to make the devices accessible.
There is a check in the kernel in sg_build_indirect() exactly for this situation: [drivers/scsi/sg.c] if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO)) gfp_mask |= __GFP_ZERO; This means non-root user will get zero-ed pages even if it has o+rw access to /dev/sg*. Tests of your reproducer on systems available to me confirm this, i.e. non-root user gets a zero-ed out buffer even if it is able to access /dev/sg*. I may not got smth correctly, but for now I do not see CVE-2018-1000204 as a security flaw and I believe a reject request to MITRE should be issued. Best regards, Vladis Dronov | Red Hat, Inc. | Product Security Engineer
Current thread:
- CVE-2018-1000204: Linux kernel 3.18 to 4.16 infoleak due to incorrect handling of SG_IO ioctl Alexander Potapenko (Jun 08)
- Re: CVE-2018-1000204: Linux kernel 3.18 to 4.16 infoleak due to incorrect handling of SG_IO ioctl Vladis Dronov (Jun 22)
- Re: CVE-2018-1000204: Linux kernel 3.18 to 4.16 infoleak due to incorrect handling of SG_IO ioctl Alexander Potapenko (Jun 26)
- Re: CVE-2018-1000204: Linux kernel 3.18 to 4.16 infoleak due to incorrect handling of SG_IO ioctl Vladis Dronov (Jun 22)