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CVE-2022-49607 Affecting kernel-debug package, versions *

Severity

 Recommended
0.0
medium
0
10

Based on CentOS security rating.

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  • Snyk IDSNYK-CENTOS7-KERNELDEBUG-8858592
  • published28 Feb 2025
  • disclosed26 Feb 2025
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Introduced: 26 Feb 2025

NewCVE-2022-49607  (opens in a new tab)

How to fix?

There is no fixed version for Centos:7 kernel-debug.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-debug package and not the kernel-debug package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

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

perf/core: Fix data race between perf_event_set_output() and perf_mmap_close()

Yang Jihing reported a race between perf_event_set_output() and perf_mmap_close():

CPU1					CPU2


perf_mmap_close(e2)
  if (atomic_dec_and_test(&e2->rb->mmap_count)) // 1 - > 0
    detach_rest = true


                ioctl(e1, IOC_SET_OUTPUT, e2)
                  perf_event_set_output(e1, e2)



  ...
  list_for_each_entry_rcu(e, &e2->rb->event_list, rb_entry)
    ring_buffer_attach(e, NULL);
    // e1 isn't yet added and
    // therefore not detached


                    ring_buffer_attach(e1, e2->rb)
                      list_add_rcu(&e1->rb_entry,
                           &e2->rb->event_list)

After this; e1 is attached to an unmapped rb and a subsequent perf_mmap() will loop forever more:

again:
    mutex_lock(&e->mmap_mutex);
    if (event->rb) {
        ...
        if (!atomic_inc_not_zero(&e->rb->mmap_count)) {
            ...
            mutex_unlock(&e->mmap_mutex);
            goto again;
        }
    }

The loop in perf_mmap_close() holds e2->mmap_mutex, while the attach in perf_event_set_output() holds e1->mmap_mutex. As such there is no serialization to avoid this race.

Change perf_event_set_output() to take both e1->mmap_mutex and e2->mmap_mutex to alleviate that problem. Additionally, have the loop in perf_mmap() detach the rb directly, this avoids having to wait for the concurrent perf_mmap_close() to get around to doing it to make progress.

CVSS Scores

version 3.1