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Medium · 5.5 CVE-2025-21922 EUVD-2025-9399GHSA-6g9c-7jcv-4g45

ppp: Fix KMSAN uninit-value warning with bpf

Published Apr 1, 2025 · Updated May 11, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: kernel Package: linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.15 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.4 Package: linux-aws-5.8 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-aws-fips Package: linux-aws-hwe Package: linux-azure Package: linux-azure-4.15 Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.15 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.4 Package: linux-azure-5.8 Package: linux-azure-6.11 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.2 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-4.15 Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.15 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.4 Package: linux-gcp-5.8 Package: linux-gcp-6.11 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gcp-fips Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.15 Package: linux-hwe-5.19 Package: linux-hwe-5.4 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-5.15 Package: linux-ibm-5.4 Package: linux-ibm-6.8 Package: linux-intel Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-intel-iotg-5.15 Package: linux-iot Package: linux-kvm Package: linux-lowlatency Package: linux-lowlatency-hwe-5.15 Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.11 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-lowlatency-hwe-6.8 Package: linux-lts-xenial Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-nvidia-tegra-5.15 Package: linux-nvidia-tegra-igx Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.11 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.15 Package: linux-oracle-5.3 Package: linux-oracle-5.4 Package: linux-oracle-5.8 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-raspi Package: linux-raspi-5.4 Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.15 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Package: linux-xilinx Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Azure Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

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

ppp: Fix KMSAN uninit-value warning with bpf

Syzbot caught an "KMSAN: uninit-value" warning [1], which is caused by the
ppp driver not initializing a 2-byte header when using socket filter.

The following code can generate a PPP filter BPF program:
'''
struct bpf_program fp;
pcap_t *handle;
handle = pcap_open_dead(DLT_PPP_PPPD, 65535);
pcap_compile(handle, &fp, "ip and outbound", 0, 0);
bpf_dump(&fp, 1);
'''
Its output is:
'''
(000) ldh [2]
(001) jeq #0x21 jt 2 jf 5
(002) ldb [0]
(003) jeq #0x1 jt 4 jf 5
(004) ret #65535
(005) ret #0
'''
Wen can find similar code at the following link:
https://github.com/ppp-project/ppp/blob/master/pppd/options.c#L1680
The maintainer of this code repository is also the original maintainer
of the ppp driver.

As you can see the BPF program skips 2 bytes of data and then reads the
'Protocol' field to determine if it's an IP packet. Then it read the first
byte of the first 2 bytes to determine the direction.

The issue is that only the first byte indicating direction is initialized
in current ppp driver code while the second byte is not initialized.

For normal BPF programs generated by libpcap, uninitialized data won't be
used, so it's not a problem. However, for carefully crafted BPF programs,
such as those generated by syzkaller [2], which start reading from offset
0, the uninitialized data will be used and caught by KMSAN.

[1] https://syzkaller.appspot.com/bug?extid=853242d9c9917165d791
[2] https://syzkaller.appspot.com/text?tag=ReproC&x=11994913980000

Affected products

VendorProductAffectedFixed
Linux Linux 2.6.12 5.4.291

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 linux 6.12.19-1 —
Debian 13 linux 6.12.19-1 —
Debian 12 linux 6.1.133-1 DSA-5900-1
Debian 11 linux 5.10.237-1 DLA-4178-1
Debian 11 linux-6.1 6.1.137-1~deb11u1 DLA-4193-1
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1066.68 —
Ubuntu 24.04 LTS linux 6.8.0-84.84 USN-7764-1
Ubuntu 24.04 LTS linux-aws 6.8.0-1039.41 USN-7764-1
Ubuntu 24.04 LTS linux-azure 6.8.0-1038.44 USN-7802-1
Ubuntu 24.04 LTS linux-azure-6.11 6.11.0-1018.18~24.04.1 USN-7628-1
Ubuntu 24.04 LTS linux-azure-nvidia 6.8.0-1025.27 USN-7809-1
Ubuntu 24.04 LTS linux-gcp 6.8.0-1040.42 USN-7764-1
Ubuntu 24.04 LTS linux-gcp-6.11 6.11.0-1016.16~24.04.1 USN-7605-1
Ubuntu 24.04 LTS linux-gke 6.8.0-1036.40 USN-7764-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1023.25 USN-7764-1
Ubuntu 24.04 LTS linux-hwe-6.11 6.11.0-28.28~24.04.1 USN-7605-1
Ubuntu 24.04 LTS linux-ibm 6.8.0-1037.37 USN-7779-1
Ubuntu 24.04 LTS linux-intel +4 No fix yet —
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-84.84.1 USN-7764-1
Ubuntu 24.04 LTS linux-lowlatency-hwe-6.11 6.11.0-1015.16~24.04.2 USN-7605-2
Ubuntu 24.04 LTS linux-nvidia 6.8.0-1039.42 USN-7765-1
Ubuntu 24.04 LTS linux-nvidia-6.11 6.11.0-1012.12 —
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1039.42.1 USN-7765-1
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1010.10 —
Ubuntu 24.04 LTS linux-oem-6.11 6.11.0-1024.24 USN-7606-1
Ubuntu 24.04 LTS linux-oracle 6.8.0-1037.38 USN-7801-2
Ubuntu 24.04 LTS linux-raspi 6.8.0-1039.43 USN-7790-1
Ubuntu 24.04 LTS linux-xilinx 6.8.0-1018.19 —
Ubuntu 22.04 LTS linux +1 5.15.0-140.150 USN-7510-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1084.91 USN-7510-7
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1039.41~22.04.1 USN-7766-1
Ubuntu 22.04 LTS linux-azure 5.15.0-1089.98 USN-7510-3
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1036.42~22.04.1 USN-7802-1
Ubuntu 22.04 LTS linux-azure-fde 5.15.0-1089.98.1 —
Ubuntu 22.04 LTS linux-gcp 5.15.0-1083.92 USN-7511-1
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1040.42~22.04.1 USN-7766-1
Ubuntu 22.04 LTS linux-gke +1 5.15.0-1081.87 USN-7511-3, USN-7510-1
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1066.74 USN-7510-1
Ubuntu 22.04 LTS linux-hwe-6.8 6.8.0-85.85~22.04.1 USN-7801-1, USN-7764-2
Ubuntu 22.04 LTS linux-ibm 5.15.0-1076.79 USN-7510-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1037.37~22.04.1 USN-7779-1
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1079.85 USN-7510-1
Ubuntu 22.04 LTS linux-kvm 5.15.0-1080.85 USN-7510-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-84.84.1~22.04.1 USN-7764-1
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1078.79 USN-7510-1
Ubuntu 22.04 LTS linux-nvidia-6.8 6.8.0-1039.42~22.04.1 USN-7765-1
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1037.37 USN-7510-3
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1026.26 USN-7510-7
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1037.38~22.04.1 USN-7801-3
Ubuntu 22.04 LTS linux-raspi 5.15.0-1078.81 USN-7510-7
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 22.04 LTS linux-riscv-6.8 6.8.0-84.84~22.04.1 —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1050.54 USN-7602-1
Ubuntu 20.04 LTS linux 5.4.0-216.236 USN-7516-1
Ubuntu 20.04 LTS linux-aws 5.4.0-1146.156 USN-7516-9
Ubuntu 20.04 LTS linux-aws-5.15 5.15.0-1084.91~20.04.1 USN-7510-8
Ubuntu 20.04 LTS linux-azure 5.4.0-1151.158 USN-7516-3
Ubuntu 20.04 LTS linux-azure-5.15 5.15.0-1089.98~20.04.1 USN-7510-3
Ubuntu 20.04 LTS linux-bluefield 5.4.0-1105.112 USN-7517-3
Ubuntu 20.04 LTS linux-gcp 5.4.0-1149.158 USN-7516-1
Ubuntu 20.04 LTS linux-gcp-5.15 5.15.0-1083.92~20.04.1 USN-7512-1
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 20.04 LTS linux-ibm 5.4.0-1092.97 USN-7516-6
Ubuntu 20.04 LTS linux-ibm-5.15 5.15.0-1076.79~20.04.1 USN-7510-1
Ubuntu 20.04 LTS linux-intel-iotg-5.15 5.15.0-1079.85~20.04.1 USN-7510-7
Ubuntu 20.04 LTS linux-kvm 5.4.0-1133.142 USN-7516-3
Ubuntu 20.04 LTS linux-lowlatency-hwe-5.15 5.15.0-140.150~20.04.1 USN-7510-1
Ubuntu 20.04 LTS linux-oracle 5.4.0-1144.154 USN-7516-1
Ubuntu 20.04 LTS linux-oracle-5.15 5.15.0-1081.87~20.04.1 USN-7510-1
Ubuntu 20.04 LTS linux-raspi 5.4.0-1129.142 USN-7539-1
Ubuntu 20.04 LTS linux-riscv-5.15 5.15.0-1079.83~20.04.1 —
Ubuntu 20.04 LTS linux-xilinx-zynqmp 5.4.0-1064.68 USN-7517-1
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Show 16 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2030.31 USN-7800-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1034.35 USN-7767-1
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1077.79 USN-7510-4
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1084.93 USN-7510-4
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1034.35~22.04.1 USN-7767-2
Ubuntu Pro FIPS 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS 18.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS 16.04 LTS linux-fips No fix yet —
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1039.41+fips1 —
Ubuntu Pro FIPS-updates 24.04 LTS linux-azure-fips 6.8.0-1040.46+fips1 —
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-84.84+fips1 —
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips 6.8.0-1040.42+fips1 —
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1084.91+fips1 USN-7510-6
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1089.98+fips1 USN-7510-5
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-140.150+fips1 USN-7510-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1083.92+fips1 USN-7511-2
Ubuntu Pro FIPS-updates 20.04 LTS linux-aws-fips 5.4.0-1146.156+fips1 USN-7516-8
Ubuntu Pro FIPS-updates 20.04 LTS linux-azure-fips 5.4.0-1151.158+fips1 USN-7518-1
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips 5.4.0-1120.130 USN-7516-8
Ubuntu Pro FIPS-updates 20.04 LTS linux-gcp-fips 5.4.0-1149.158+fips1 USN-7516-2
Ubuntu Pro FIPS-updates 18.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 16.04 LTS linux-fips No fix yet —
Ubuntu Pro FIPS-preview 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 20.04 LTS linux-hwe-5.15 5.15.0-142.152~20.04.1 USN-7593-1
Ubuntu Pro 20.04 LTS linux-iot 5.4.0-1051.54 USN-7640-1
Ubuntu Pro 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1039.39~20.04.1 —
Ubuntu Pro 18.04 LTS linux +5 No fix yet —
Ubuntu Pro 18.04 LTS linux-aws-5.4 5.4.0-1146.156~18.04.1 USN-7516-7
Ubuntu Pro 18.04 LTS linux-azure-5.4 5.4.0-1151.158~18.04.1 USN-7516-1
Ubuntu Pro 18.04 LTS linux-gcp-5.4 5.4.0-1149.158~18.04.1 USN-7516-1
Ubuntu Pro 18.04 LTS linux-hwe-5.4 5.4.0-216.236~18.04.1 USN-7516-5
Ubuntu Pro 18.04 LTS linux-ibm-5.4 5.4.0-1092.97~18.04.1 USN-7517-2
Ubuntu Pro 18.04 LTS linux-oracle-5.4 5.4.0-1144.154~18.04.1 USN-7516-4
Ubuntu Pro 18.04 LTS linux-raspi-5.4 5.4.0-1129.142~18.04.1 USN-7540-1
Ubuntu Pro 16.04 LTS linux +7 No fix yet —
Ubuntu Pro 14.04 LTS linux +3 No fix yet —
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +6 6.4.0-150700.53.3.1 SUSE-SU-2025:01951-1
SLES 15 SP7 kernel-azure +2 6.4.0-150700.20.3.1 SUSE-SU-2025:01967-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.3.1.150700.17.2.1 SUSE-SU-2025:01951-1
SLES 15 SP6 kernel-64kb +6 6.4.0-150600.23.50.1 SUSE-SU-2025:01614-1
SLES 15 SP6 kernel-azure +2 6.4.0-150600.8.37.1 SUSE-SU-2025:01707-1
SLES 15 SP6 kernel-coco +3 6.4.0-15061.21.coco15sp6.1 SUSE-SU-2025:01919-1
SLES 15 SP6 kernel-default-base 6.4.0-150600.23.50.1.150600.12.22.1 SUSE-SU-2025:01614-1
SLES 12 SP5 kernel-syms +2 4.12.14-122.255.1 SUSE-SU-2025:1293-1
Show 6 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLE Micro 6.1 kernel-default-base 6.4.0-28.1.21.6 SUSE-SU-2025:20270-1
SLE Micro 6.1 kernel-livepatch-MICRO-6-0-RT_Update_7 1-1.3 SUSE-SU-2025:20283-1
SLE Micro 6.1 kernel-livepatch-MICRO-6-0_Update_6 1-3.1 SUSE-SU-2025:20270-1
SLE Micro 6.1 kernel-rt +1 6.4.0-30.1 SUSE-SU-2025:20283-1
SLE Micro 6.1 kernel-source +2 6.4.0-28.1 SUSE-SU-2025:20270-1
SLE Micro 6.0 kernel-default-base 6.4.0-28.1.21.6 SUSE-SU-2025:20192-1
SLE Micro 6.0 kernel-livepatch-MICRO-6-0-RT_Update_7 1-1.3 SUSE-SU-2025:20206-1
SLE Micro 6.0 kernel-livepatch-MICRO-6-0_Update_6 1-3.1 SUSE-SU-2025:20192-1
SLE Micro 6.0 kernel-rt +1 6.4.0-30.1 SUSE-SU-2025:20206-1
SLE Micro 6.0 kernel-source +2 6.4.0-28.1 SUSE-SU-2025:20192-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.3.1 SUSE-SU-2025:01951-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_1 1-150700.15.3.1 SUSE-SU-2025:01951-1
SLE Live Patching 15 SP6 kernel-default 6.4.0-150600.23.50.1 SUSE-SU-2025:01614-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6-RT_Update_11 1-150600.1.3.2 SUSE-SU-2025:01964-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_11 1-150600.13.3.1 SUSE-SU-2025:01614-1
SLE Live Patching 12 SP5 kernel-default 4.12.14-122.255.1 SUSE-SU-2025:1293-1
SLE Live Patching 12 SP5 kgraft-patch-SLE12-SP5_Update_67 1-8.5.1 SUSE-SU-2025:1293-1
SUSE Real Time Module 15 SP6 kernel-rt +3 6.4.0-150600.10.39.1 SUSE-SU-2025:01964-1
ReleasePackageFixed inAdvisory
openSUSE Leap 15.6 dtb-aarch64 +10 6.4.0-150600.23.50.1 SUSE-SU-2025:01614-1
openSUSE Leap 15.6 kernel-azure +2 6.4.0-150600.8.37.1 SUSE-SU-2025:01707-1
openSUSE Leap 15.6 kernel-default-base 6.4.0-150600.23.50.1.150600.12.22.1 SUSE-SU-2025:01614-1
openSUSE Leap 15.6 kernel-rt +3 6.4.0-150600.10.39.1 SUSE-SU-2025:01964-1

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 kernel 6.6.85.1-2 —
Azure Linux 2 (CBL-Mariner) kernel 5.15.180.1-1 —

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-101.33.4.3.el10uek ELSA-2025-20530, ELSA-2025-20480

Advisories 50

References