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Fencer Vulns
critical 9.8

CVE-2022-49093 in the critical feed json

skbuff: fix coalescing for page_pool fragment recycling

published 2025-02-26 20 mo ago modified 2026-08-05 3 mo ago also EUVD-2022-55111

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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

skbuff: fix coalescing for page_pool fragment recycling

Fix a use-after-free when using page_pool with page fragments. We encountered this problem during normal RX in the hns3 driver:

(1) Initially we have three descriptors in the RX queue. The first one allocates PAGE1 through page_pool, and the other two allocate one half of PAGE2 each. Page references look like this:

RX_BD1 _______ PAGE1 RX_BD2 _______ PAGE2 RX_BD3 _________/

(2) Handle RX on the first descriptor. Allocate SKB1, eventually added to the receive queue by tcp_queue_rcv().

(3) Handle RX on the second descriptor. Allocate SKB2 and pass it to netif_receive_skb():

netif_receive_skb(SKB2) ip_rcv(SKB2) SKB3 = skb_clone(SKB2)

SKB2 and SKB3 share a reference to PAGE2 through skb_shinfo()->dataref. The other ref to PAGE2 is still held by RX_BD3:

SKB2 ---+- PAGE2 SKB3 __/ / RX_BD3 _________/

(3b) Now while handling TCP, coalesce SKB3 with SKB1:

tcp_v4_rcv(SKB3) tcp_try_coalesce(to=SKB1, from=SKB3) // succeeds kfree_skb_partial(SKB3) skb_release_data(SKB3) // drops one dataref

SKB1 _____ PAGE1 \____ SKB2 _____ PAGE2 / RX_BD3 _________/

In skb_try_coalesce(), __skb_frag_ref() takes a page reference to PAGE2, where it should instead have increased the page_pool frag reference, pp_frag_count. Without coalescing, when releasing both SKB2 and SKB3, a single reference to PAGE2 would be dropped. Now when releasing SKB1 and SKB2, two references to PAGE2 will be dropped, resulting in underflow.

(3c) Drop SKB2:

af_packet_rcv(SKB2) consume_skb(SKB2) skb_release_data(SKB2) // drops second dataref page_pool_return_skb_page(PAGE2) // drops one pp_frag_count

SKB1 _____ PAGE1 \____ PAGE2 / RX_BD3 _________/

(4) Userspace calls recvmsg() Copies SKB1 and releases it. Since SKB3 was coalesced with SKB1, we release the SKB3 page as well:

tcp_eat_recv_skb(SKB1) skb_release_data(SKB1) page_pool_return_skb_page(PAGE1) page_pool_return_skb_page(PAGE2) // drops second pp_frag_count

(5) PAGE2 is freed, but the third RX descriptor was still using it! In our case this causes IOMMU faults, but it would silently corrupt memory if the IOMMU was disabled.

Change the logic that checks whether pp_recycle SKBs can be coalesced. We still reject differing pp_recycle between 'from' and 'to' SKBs, but in order to avoid the situation described above, we also reject coalescing when both 'from' and 'to' are pp_recycled and 'from' is cloned.

The new logic allows coalescing a cloned pp_recycle SKB into a page refcounted one, because in this case the release (4) will drop the right reference, the one taken by skb_try_coalesce().

Patch / fix

  • Linux Linux 5.15.34, 5.16.20, 5.17.3, 5.18
  • linux Debian 14, Debian 13, Debian 12 5.17.3-1

debian advisories DEBIAN-CVE-2022-49093

  • linux Ubuntu 22.04 LTS 5.15.0-37.39
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1011.14
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1008.12
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1008.10
  • linux-ibm Ubuntu 22.04 LTS 5.15.0-1007.8
  • linux-kvm Ubuntu 22.04 LTS 5.15.0-1010.11
  • linux-azure Ubuntu 22.04 LTS 5.15.0-1010.12
  • linux-raspi Ubuntu 22.04 LTS 5.15.0-1011.13

ubuntu advisories UBUNTU-CVE-2022-49093

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 RHEL 9 5.14.0-162.6.1.el9_1
  • perf RHEL 9 5.14.0-162.6.1.el9_1
  • bpftool RHEL 9 5.14.0-162.6.1.el9_1
  • kernel-core RHEL 9 5.14.0-162.6.1.el9_1
  • kernel-tools RHEL 9 5.14.0-162.6.1.el9_1
  • python3-perf RHEL 9 5.14.0-162.6.1.el9_1
  • kernel-modules RHEL 9 5.14.0-162.6.1.el9_1
  • kernel-zfcpdump RHEL 9 5.14.0-162.6.1.el9_1

red hat advisories RHSA-2022:8267

  • kernel-64kb SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS, SLE High Performance Computing 15 SP5-ESPOS 5.14.21-150500.55.100.1
  • kernel-syms SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 5.14.21-150500.55.100.1
  • kernel-source SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 5.14.21-150500.55.100.1
  • kernel-default SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +3 more 5.14.21-150500.55.100.1
  • kernel-obs-build SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 5.14.21-150500.55.100.1
  • kernel-default-base SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 5.14.21-150500.55.100.1.150500.6.47.1
  • kernel-rt SLE Micro 5.4, SLE Micro 5.3 5.14.21-150400.15.115.1
  • kernel-source-rt SLE Micro 5.4, SLE Micro 5.3 5.14.21-150400.15.115.1

suse advisories SUSE-SU-2025:1241-1SUSE-SU-2025:1183-1SUSE-SU-2025:1176-1SUSE-SU-2025:1027-1

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-2022-49093 updated cvss 7.0

kernel: skbuff: fix coalescing for page_pool fragment recycling

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 9) kernel-debuginfo-common-s390x 5.14.0-162.6.1.el9_1, kernel-debuginfo-common-x86_64 5.14.0-162.6.1.el9_1, kernel-debuginfo-common-aarch64 5.14.0-162.6.1.el9_1, kernel-debuginfo-common-ppc64le 5.14.0-162.6.1.el9_1 Red Hat Enterprise Linux AppStream (v. 9) perf 5.14.0-162.6.1.el9_1, kernel-devel-matched 5.14.0-162.6.1.el9_1, kernel-debug-devel-matched 5.14.0-162.6.1.el9_1, kernel-debuginfo-common-s390x 5.14.0-162.6.1.el9_1, kernel-zfcpdump-devel-matched 5.14.0-162.6.1.el9_1, kernel-debuginfo-common-x86_64 5.14.0-162.6.1.el9_1, +2 more Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-162.6.1.el9_1, bpftool 5.14.0-162.6.1.el9_1, kernel-core 5.14.0-162.6.1.el9_1, kernel-tools 5.14.0-162.6.1.el9_1, python3-perf 5.14.0-162.6.1.el9_1, kernel-modules 5.14.0-162.6.1.el9_1, +14 more
    fixed: vendor fix RHSA-2022:8267
  • 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 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
20 mo ago

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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.