Linux Kernel version 3.18 to 4.16 incorrectly handles an SG_IO...

Vulnerability Description

Linux Kernel version 3.18 to 4.16 incorrectly handles an SG_IO ioctl on /dev/sg0 with dxfer_direction=SG_DXFER_FROM_DEV and an empty 6-byte cmdp. This may lead to copying up to 1000 kernel heap pages to the userspace. This has been fixed upstream in https://github.com/torvalds/linux/commit/a45b599ad808c3c982fdcdc12b0b8611c2f92824 already. 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. NOTE: third parties dispute the relevance of this report, noting that the requirement for an attacker to have both the CAP_SYS_ADMIN and CAP_SYS_RAWIO capabilities makes it "virtually impossible to exploit.

References

• https://usn.ubuntu.com/3752-2/
• https://lists.debian.org/debian-lts-announce/2018/07/msg00015.html
• https://usn.ubuntu.com/3696-1/
• https://usn.ubuntu.com/3752-3/
• https://lists.debian.org/debian-lts-announce/2018/07/msg00016.html
• http://www.openwall.com/lists/oss-security/2018/06/26/3
• https://usn.ubuntu.com/3754-1/
• https://lists.debian.org/debian-lts-announce/2018/07/msg00020.html
• https://access.redhat.com/errata/RHSA-2018:2948
• https://github.com/torvalds/linux/commit/a45b599ad808c3c982fdcdc12b0b8611c2f92824
• https://usn.ubuntu.com/3696-2/
• https://usn.ubuntu.com/3752-1/
• http://lists.opensuse.org/opensuse-security-announce/2019-05/msg00043.html