# CVE-2022-50620: linux: In the Linux kernel, the following vulnerability has been resolved:  f2fs: fix to invalidate dcc->f2fs_issue_discard...

CVE-2022-50620 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-50620, released December 8, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-50620
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0021
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 8, 2025

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.4-1 | [DEBIAN-CVE-2022-50620](https://patchblox.com/security/data/fix/linux/debian-cve-2022-50620.md) | Dec 8, 2025 |
| Linux | linux Debian 13.5 (trixie) | 6.1.4-1 | [DEBIAN-CVE-2022-50620](https://patchblox.com/security/data/fix/linux/debian-cve-2022-50620.md) | Dec 8, 2025 |
| Linux | linux Debian 14 | 6.1.4-1 | [DEBIAN-CVE-2022-50620](https://patchblox.com/security/data/fix/linux/debian-cve-2022-50620.md) | Dec 8, 2025 |

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