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Fencer Vulns
medium 5.5

CVE-2021-47590 json

mptcp: fix deadlock in __mptcp_push_pending()

published 2024-06-19 2 y ago modified 2026-06-17 4 mo ago also EUVD-2021-34592

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

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

mptcp: fix deadlock in __mptcp_push_pending()

__mptcp_push_pending() may call mptcp_flush_join_list() with subflow socket lock held. If such call hits mptcp_sockopt_sync_all() then subsequently __mptcp_sockopt_sync() could try to lock the subflow socket for itself, causing a deadlock.

sysrq: Show Blocked State task:ss-server state:D stack: 0 pid: 938 ppid: 1 flags:0x00000000 Call Trace: <TASK> __schedule+0x2d6/0x10c0 ? __mod_memcg_state+0x4d/0x70 ? csum_partial+0xd/0x20 ? _raw_spin_lock_irqsave+0x26/0x50 schedule+0x4e/0xc0 __lock_sock+0x69/0x90 ? do_wait_intr_irq+0xa0/0xa0 __lock_sock_fast+0x35/0x50 mptcp_sockopt_sync_all+0x38/0xc0 __mptcp_push_pending+0x105/0x200 mptcp_sendmsg+0x466/0x490 sock_sendmsg+0x57/0x60 __sys_sendto+0xf0/0x160 ? do_wait_intr_irq+0xa0/0xa0 ? fpregs_restore_userregs+0x12/0xd0 __x64_sys_sendto+0x20/0x30 do_syscall_64+0x38/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f9ba546c2d0 RSP: 002b:00007ffdc3b762d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f9ba56c8060 RCX: 00007f9ba546c2d0 RDX: 000000000000077a RSI: 0000000000e5e180 RDI: 0000000000000234 RBP: 0000000000cc57f0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9ba56c8060 R13: 0000000000b6ba60 R14: 0000000000cc7840 R15: 41d8685b1d7901b8 </TASK>

Fix the issue by using __mptcp_flush_join_list() instead of plain mptcp_flush_join_list() inside __mptcp_push_pending(), as suggested by Florian. The sockopt sync will be deferred to the workqueue.

Patch / fix

  • Linux Linux 5.15.11, 5.16
  • linux Debian 14, Debian 13, Debian 12 5.15.15-1

debian advisories DEBIAN-CVE-2021-47590

  • kernel RHEL 8 4.18.0-372.9.1.el8
  • perf RHEL 8 4.18.0-372.9.1.el8
  • bpftool RHEL 8 4.18.0-372.9.1.el8
  • kernel-core RHEL 8 4.18.0-372.9.1.el8
  • kernel-tools RHEL 8 4.18.0-372.9.1.el8
  • python3-perf RHEL 8 4.18.0-372.9.1.el8
  • kernel-modules RHEL 8 4.18.0-372.9.1.el8
  • kernel-zfcpdump RHEL 8 4.18.0-372.9.1.el8

red hat advisories RHSA-2022:1988RHSA-2022:1975

  • kernel-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.63.1
  • kernel-syms-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.63.1
  • kernel-source-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.63.1
  • dtb-aarch64 openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-64kb SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-syms SLE Module for Development Tools 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-obs-qa openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-source SLE Module for Development Tools 15 SP5, SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1

suse advisories SUSE-SU-2024:2947-1SUSE-SU-2024:2939-1SUSE-SU-2024:2894-1

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-2021-47590 updated cvss 5.5

kernel: mptcp: fix deadlock in __mptcp_push_pending()

  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-372.9.1.el8, kernel 4.18.0-372.9.1.el8, bpftool 4.18.0-372.9.1.el8, kernel-core 4.18.0-372.9.1.el8, kernel-tools 4.18.0-372.9.1.el8, python3-perf 4.18.0-372.9.1.el8, +15 more Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-372.9.1.el8, kernel-debuginfo-common-aarch64 4.18.0-372.9.1.el8, kernel-debuginfo-common-ppc64le 4.18.0-372.9.1.el8
    fixed: vendor fix RHSA-2022:1988
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-372.9.1.rt7.166.el8, kernel-rt-kvm 4.18.0-372.9.1.rt7.166.el8, kernel-rt-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-kvm 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-core 4.18.0-372.9.1.rt7.166.el8, +4 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-372.9.1.rt7.166.el8, kernel-rt-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules-extra 4.18.0-372.9.1.rt7.166.el8, +2 more
    fixed: vendor fix RHSA-2022:1975
  • 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 9 rv, perf, rtla, kernel, bpftool, libperf, +83 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

0.16% chance of exploitation in the next 30 days, higher than 4% 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.