nvme: fix command effects log lifetime for multipath heads

Overview

In the Linux kernel, the following vulnerability has been resolved:

nvme: fix command effects log lifetime for multipath heads

KASAN reported a use-after-free when an I/O passthrough command was sent through a multipath namespace head after the controller path that first created the head had been removed:

BUG: KASAN: slab-use-after-free in nvme_command_effects+0x192/0x200 [nvme_core] Read of size 4 at addr ffff888141b14400 by task nvme/19811 nvme_command_effects+0x192/0x200 [nvme_core] nvme_cmd_allowed+0x7e/0x1b0 [nvme_core] nvme_user_cmd.constprop.0+0x1b5/0x450 [nvme_core] nvme_ns_head_chr_ioctl+0xf4/0x2a0 [nvme_core]

Move the log cache to the subsystem, with one entry per command set. Both controllers and namespace heads hold subsystem references, keeping their log pointers valid until subsystem release.

Affected

• Linux >= be93e87e780253780df9bb6ecc9bc1199b0d94c3 < 351d1c47e45b2b35780d0548b1012d7242ba298d
• Linux >= be93e87e780253780df9bb6ecc9bc1199b0d94c3 < 72ece656abd4de8645a421fb482d7a11e6533a45
• Linux 5.9

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.