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Fencer Vulns
medium 5.5

CVE-2022-48983 json

io_uring: Fix a null-ptr-deref in io_tctx_exit_cb()

published 2024-10-21 2 y ago modified 2026-06-17 4 mo ago also EUVD-2022-53862

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

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

io_uring: Fix a null-ptr-deref in io_tctx_exit_cb()

Syzkaller reports a NULL deref bug as follows:

BUG: KASAN: null-ptr-deref in io_tctx_exit_cb+0x53/0xd3 Read of size 4 at addr 0000000000000138 by task file1/1955

CPU: 1 PID: 1955 Comm: file1 Not tainted 6.1.0-rc7-00103-gef4d3ea40565 #75 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0xcd/0x134 ? io_tctx_exit_cb+0x53/0xd3 kasan_report+0xbb/0x1f0 ? io_tctx_exit_cb+0x53/0xd3 kasan_check_range+0x140/0x190 io_tctx_exit_cb+0x53/0xd3 task_work_run+0x164/0x250 ? task_work_cancel+0x30/0x30 get_signal+0x1c3/0x2440 ? lock_downgrade+0x6e0/0x6e0 ? lock_downgrade+0x6e0/0x6e0 ? exit_signals+0x8b0/0x8b0 ? do_raw_read_unlock+0x3b/0x70 ? do_raw_spin_unlock+0x50/0x230 arch_do_signal_or_restart+0x82/0x2470 ? kmem_cache_free+0x260/0x4b0 ? putname+0xfe/0x140 ? get_sigframe_size+0x10/0x10 ? do_execveat_common.isra.0+0x226/0x710 ? lockdep_hardirqs_on+0x79/0x100 ? putname+0xfe/0x140 ? do_execveat_common.isra.0+0x238/0x710 exit_to_user_mode_prepare+0x15f/0x250 syscall_exit_to_user_mode+0x19/0x50 do_syscall_64+0x42/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0023:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 002b:00000000fffb7790 EFLAGS: 00000200 ORIG_RAX: 000000000000000b RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> Kernel panic - not syncing: panic_on_warn set ...

This happens because the adding of task_work from io_ring_exit_work() isn't synchronized with canceling all work items from eg exec. The execution of the two are ordered in that they are both run by the task itself, but if io_tctx_exit_cb() is queued while we're canceling all work items off exec AND gets executed when the task exits to userspace rather than in the main loop in io_uring_cancel_generic(), then we can find current->io_uring == NULL and hit the above crash.

It's safe to add this NULL check here, because the execution of the two paths are done by the task itself.

[axboe: add code comment and also put an explanation in the commit msg]

Patch / fix

  • Linux Linux 5.15.83, 6.0.13, 6.1
  • linux Debian 14, Debian 13, Debian 12 6.1.4-1

debian advisories DEBIAN-CVE-2022-48983

  • linux Ubuntu 22.04 LTS 5.15.0-67.74
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1031.35
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1030.37
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1028.33
  • linux-ibm Ubuntu 22.04 LTS 5.15.0-1026.29
  • linux-kvm Ubuntu 22.04 LTS 5.15.0-1029.34
  • linux-azure Ubuntu 22.04 LTS 5.15.0-1034.41
  • linux-gkeop Ubuntu 22.04 LTS 5.15.0-1016.21

ubuntu advisories UBUNTU-CVE-2022-48983

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

  • kernel-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.75.1
  • kernel-syms-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.75.1
  • kernel-source-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.75.1
  • kernel-64kb SLE Module for Basesystem 15 SP5 5.14.21-150500.55.88.1
  • kernel-syms SLE Module for Development Tools 15 SP5 5.14.21-150500.55.88.1
  • kernel-source SLE Module for Development Tools 15 SP5, SLE Module for Basesystem 15 SP5 5.14.21-150500.55.88.1
  • kernel-default SLE Module for Legacy 15 SP5, SLE Module for Basesystem 15 SP5, SLE Micro 5.5 +2 more 5.14.21-150500.55.88.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP5 5.14.21-150500.55.88.1

suse advisories SUSE-SU-2024:4376-1SUSE-SU-2024:4364-1SUSE-SU-2024:4315-1

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-2022-48983 updated cvss 5.5

kernel: io_uring: Fix a null-ptr-deref in io_tctx_exit_cb()

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    affected: no fix available
  • 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
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
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.