Subject: CVE-2024-35989: dmaengine: idxd: Fix oops during rmmod on single-CPU platforms

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

dmaengine: idxd: Fix oops during rmmod on single-CPU platforms

During the removal of the idxd driver, registered offline callback is
invoked as part of the clean up process. However, on systems with only
one CPU online, no valid target is available to migrate the
perf context, resulting in a kernel oops:

    BUG: unable to handle page fault for address: 000000000002a2b8
    #PF: supervisor write access in kernel mode
    #PF: error_code(0x0002) - not-present page
    PGD 1470e1067 P4D 0
    Oops: 0002 [#1] PREEMPT SMP NOPTI
    CPU: 0 PID: 20 Comm: cpuhp/0 Not tainted 6.8.0-rc6-dsa+ #57
    Hardware name: Intel Corporation AvenueCity/AvenueCity, BIOS BHSDCRB1.86B.2492.D03.2307181620 07/18/2023
    RIP: 0010:mutex_lock+0x2e/0x50
    ...
    Call Trace:
    <TASK>
    __die+0x24/0x70
    page_fault_oops+0x82/0x160
    do_user_addr_fault+0x65/0x6b0
    __pfx___rdmsr_safe_on_cpu+0x10/0x10
    exc_page_fault+0x7d/0x170
    asm_exc_page_fault+0x26/0x30
    mutex_lock+0x2e/0x50
    mutex_lock+0x1e/0x50
    perf_pmu_migrate_context+0x87/0x1f0
    perf_event_cpu_offline+0x76/0x90 [idxd]
    cpuhp_invoke_callback+0xa2/0x4f0
    __pfx_perf_event_cpu_offline+0x10/0x10 [idxd]
    cpuhp_thread_fun+0x98/0x150
    smpboot_thread_fn+0x27/0x260
    smpboot_thread_fn+0x1af/0x260
    __pfx_smpboot_thread_fn+0x10/0x10
    kthread+0x103/0x140
    __pfx_kthread+0x10/0x10
    ret_from_fork+0x31/0x50
    __pfx_kthread+0x10/0x10
    ret_from_fork_asm+0x1b/0x30
    <TASK>

Fix the issue by preventing the migration of the perf context to an
invalid target.

The Linux kernel CVE team has assigned CVE-2024-35989 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.13 with commit 81dd4d4d6178 and fixed in 5.15.158 with commit 9edd3aa34d50
	Issue introduced in 5.13 with commit 81dd4d4d6178 and fixed in 6.1.90 with commit 023b6390a15a
	Issue introduced in 5.13 with commit 81dd4d4d6178 and fixed in 6.6.30 with commit f976eca36cdf
	Issue introduced in 5.13 with commit 81dd4d4d6178 and fixed in 6.8.9 with commit 47533176fdce
	Issue introduced in 5.13 with commit 81dd4d4d6178 and fixed in 6.9 with commit f221033f5c24

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-35989
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/dma/idxd/perfmon.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/9edd3aa34d50f27b97be30b2ba4a6af0945ff56b
	https://git.kernel.org/stable/c/023b6390a15a98f9c3aa5e7da78d485d5384a08e
	https://git.kernel.org/stable/c/f976eca36cdf94e32fa4f865db0e7c427c9aa33c
	https://git.kernel.org/stable/c/47533176fdcef17b114a6f688bc872901c1ec6bb
	https://git.kernel.org/stable/c/f221033f5c24659dc6ad7e5cf18fb1b075f4a8be