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Fencer Vulns
medium 5.5

CVE-2021-47199 json

net/mlx5e: CT, Fix multiple allocations and memleak of mod acts

published 2024-04-10 2 y ago modified 2026-06-17 4 mo ago also EUVD-2021-33847

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 9%
public exploits
0
none known

Summary

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

net/mlx5e: CT, Fix multiple allocations and memleak of mod acts

CT clear action offload adds additional mod hdr actions to the flow's original mod actions in order to clear the registers which hold ct_state. When such flow also includes encap action, a neigh update event can cause the driver to unoffload the flow and then reoffload it.

Each time this happens, the ct clear handling adds that same set of mod hdr actions to reset ct_state until the max of mod hdr actions is reached.

Also the driver never releases the allocated mod hdr actions and causing a memleak.

Fix above two issues by moving CT clear mod acts allocation into the parsing actions phase and only use it when offloading the rule. The release of mod acts will be done in the normal flow_put().

backtrace: [<000000007316e2f3>] krealloc+0x83/0xd0 [<00000000ef157de1>] mlx5e_mod_hdr_alloc+0x147/0x300 [mlx5_core] [<00000000970ce4ae>] mlx5e_tc_match_to_reg_set_and_get_id+0xd7/0x240 [mlx5_core] [<0000000067c5fa17>] mlx5e_tc_match_to_reg_set+0xa/0x20 [mlx5_core] [<00000000d032eb98>] mlx5_tc_ct_entry_set_registers.isra.0+0x36/0xc0 [mlx5_core] [<00000000fd23b869>] mlx5_tc_ct_flow_offload+0x272/0x1f10 [mlx5_core] [<000000004fc24acc>] mlx5e_tc_offload_fdb_rules.part.0+0x150/0x620 [mlx5_core] [<00000000dc741c17>] mlx5e_tc_encap_flows_add+0x489/0x690 [mlx5_core] [<00000000e92e49d7>] mlx5e_rep_update_flows+0x6e4/0x9b0 [mlx5_core] [<00000000f60f5602>] mlx5e_rep_neigh_update+0x39a/0x5d0 [mlx5_core]

Patch / fix

  • Linux Linux 5.15.5, 5.16
  • linux Debian 14, Debian 13, Debian 12 5.15.5-1

debian advisories DEBIAN-CVE-2021-47199

  • kernel-rt SLE Micro 5.5, Real Time Module 15 SP5, openSUSE Leap 15.5 5.14.21-150500.13.52.1
  • kernel-syms-rt Real Time Module 15 SP5, openSUSE Leap 15.5 5.14.21-150500.13.52.1
  • kernel-rt_debug Real Time Module 15 SP5, openSUSE Leap 15.5 5.14.21-150500.13.52.1
  • kernel-source-rt SLE Micro 5.5, Real Time Module 15 SP5, openSUSE Leap 15.5 5.14.21-150500.13.52.1
  • dtb-aarch64 openSUSE Leap 15.5 5.14.21-150500.55.62.1
  • kernel-64kb SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.62.2
  • kernel-syms SLE Module for Development Tools 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.62.1
  • kernel-obs-qa openSUSE Leap 15.5 5.14.21-150500.55.62.1

suse advisories SUSE-SU-2024:1663-1SUSE-SU-2024:1659-1SUSE-SU-2024:1647-1SUSE-SU-2024:1644-1SUSE-SU-2024:1641-1

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-2021-47199 updated cvss 6.0

kernel: net/mlx5e: CT, Fix multiple allocations and memleak of mod acts

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: no fix planned “Out of support scope”
  • 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
    affected: no fix available
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 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

0.20% chance of exploitation in the next 30 days, higher than 9% 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
  • CWE-401 Missing Release of Memory after Effective Lifetime
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.