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Fencer Vulns
no cvss —

CVE-2022-50620 json

f2fs: fix to invalidate dcc->f2fs_issue_discard in error path

published 2025-12-08 11 mo ago modified 2026-06-17 4 mo ago also EUVD-2022-55692

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

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

f2fs: fix to invalidate dcc->f2fs_issue_discard in error path

Syzbot reports a NULL pointer dereference issue as below:

__refcount_add include/linux/refcount.h:193 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] get_task_struct include/linux/sched/task.h:110 [inline] kthread_stop+0x34/0x1c0 kernel/kthread.c:703 f2fs_stop_discard_thread+0x3c/0x5c fs/f2fs/segment.c:1638 kill_f2fs_super+0x5c/0x194 fs/f2fs/super.c:4522 deactivate_locked_super+0x70/0xe8 fs/super.c:332 deactivate_super+0xd0/0xd4 fs/super.c:363 cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186 __cleanup_mnt+0x20/0x30 fs/namespace.c:1193 task_work_run+0xc4/0x14c kernel/task_work.c:177 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0x26c/0xbe0 kernel/exit.c:795 do_group_exit+0x60/0xe8 kernel/exit.c:925 __do_sys_exit_group kernel/exit.c:936 [inline] __se_sys_exit_group kernel/exit.c:934 [inline] __wake_up_parent+0x0/0x40 kernel/exit.c:934 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

The root cause of this issue is in error path of f2fs_start_discard_thread(), it missed to invalidate dcc->f2fs_issue_discard, later kthread_stop() may access invalid pointer.

Patch / fix

  • Linux Linux 5.15.86, 6.0.16, 6.1.2, 6.2
  • linux Debian 14, Debian 13, Debian 12 6.1.4-1

debian advisories DEBIAN-CVE-2022-50620

  • linux Ubuntu 22.04 LTS 5.15.0-69.76
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1033.37
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1031.38
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1030.35
  • linux-ibm Ubuntu 22.04 LTS 5.15.0-1027.30
  • linux-kvm Ubuntu 22.04 LTS 5.15.0-1030.35
  • linux-azure Ubuntu 22.04 LTS 5.15.0-1035.42
  • linux-gkeop Ubuntu 22.04 LTS 5.15.0-1017.22

ubuntu advisories UBUNTU-CVE-2022-50620

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2022-50620 updated

kernel: f2fs: fix to invalidate dcc->f2fs_issue_discard in error path

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.