Skip to content
OpenAdvisories
Critical · 9.8 CVE-2026-64102 EUVD-2026-45787GHSA-mhgq-v2h6-4f9w

RDMA/siw: Reject MPA FPDU length underflow before signed receive math

Published Jul 19, 2026 · Updated Oct 19, 2026 · Assigned by Linux

Vendor: Linux Product: Linux 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-6.14 Package: linux-aws-6.17 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-aws-fips Package: linux-azure 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-6.14 Package: linux-azure-6.17 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-7.0 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.15 Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.17 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fde-7.0 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-azure-nvidia-6.14 Package: linux-bluefield Package: linux-fips Package: linux-gcp 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-6.14 Package: linux-gcp-6.17 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gcp-7.0 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-6.14 Package: linux-hwe-6.17 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-7.0 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-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-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-7.0 Package: linux-nvidia-bos 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-6.14 Package: linux-oem-6.17 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oem-7.0 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-6.14 Package: linux-oracle-6.17 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-oracle-7.0 Package: linux-raspi Package: linux-raspi-5.4 Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.14 Package: linux-realtime-6.17 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-6.14 Package: linux-riscv-6.17 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-riscv-7.0 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: Debian Ecosystem: Ubuntu

Description

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

RDMA/siw: Reject MPA FPDU length underflow before signed receive math

A malicious connected siw peer can send an iWARP FPDU whose MPA length
field (c_hdr->mpa_len, 16 bit big-endian, peer-controlled) is smaller
than the fixed DDP/RDMAP header for the announced opcode. Soft-iWARP
parses the full header in siw_get_hdr() based on iwarp_pktinfo[opcode]
.hdr_len, but never compares mpa_len against that header length.

siw_tcp_rx_data() then derives

srx->fpdu_part_rem = be16_to_cpu(mpa_len) - fpdu_part_rcvd
+ MPA_HDR_SIZE;

where fpdu_part_rcvd equals iwarp_pktinfo[opcode].hdr_len at this
point. For a tagged WRITE (hdr_len 16, MPA_HDR_SIZE 2) the smallest
on-wire mpa_len of 0 yields fpdu_part_rem = -14, and any mpa_len below
hdr_len - MPA_HDR_SIZE underflows to a negative int.

The signed value then flows into siw_proc_write()/siw_proc_rresp() as

bytes = min(srx->fpdu_part_rem, srx->skb_new);

is handed to siw_check_mem() as an int len (whose interval check
addr + len > mem->va + mem->len is satisfied for a valid base when
len is negative), and reaches siw_rx_data() -> siw_rx_kva() /
siw_rx_umem() -> skb_copy_bits() as a signed copy length. The header
copy branch in skb_copy_bits() promotes that to size_t, producing a
multi-gigabyte read.

KASAN under a KUnit harness that drives the real kernel TCP receive
path -- a loopback AF_INET socketpair, the malformed FPDU written via
kernel_sendmsg, sk_data_ready firing in softirq, tcp_read_sock
dispatching to siw_tcp_rx_data -- reports:

BUG: KASAN: use-after-free in skb_copy_bits+0x284/0x480
Read of size 4294967295 at addr ffff888...
Call Trace:
skb_copy_bits
siw_rx_kva
siw_rx_data
siw_check_mem
siw_proc_write
siw_tcp_rx_data
__tcp_read_sock
siw_qp_llp_data_ready
tcp_data_ready
tcp_data_queue

Add the missing invariant at the earliest point where the peer header
is fully assembled. iwarp_pktinfo[*].hdr_len - MPA_HDR_SIZE is exactly
the value the siw transmitter uses as the minimum mpa_len for each
opcode (drivers/infiniband/sw/siw/siw_qp.c:33), so this matches the
protocol contract. Out-of-range FPDUs terminate the connection with
TERM_ERROR_LAYER_LLP / LLP_ETYPE_MPA / LLP_ECODE_FPDU_START -- which
is RFC 5044 Section 8 error code 3 ("Marker and ULPDU Length fields
do not agree on the start of an FPDU"), the correct framing-error
class for this inconsistency.

Affected products

VendorProductAffectedFixed
Linux Linux 5.3 5.10.258

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 7.0.12-1 —
Debian 13 linux 6.12.94-1 —
Debian 12 linux 6.1.176-1 —
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1030.35 —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1096.98 —
Ubuntu 26.04 LTS linux 7.0.0-28.28 —
Ubuntu 26.04 LTS linux-aws +2 7.0.0-1009.9 USN-8618-1, USN-8603-1
Ubuntu 26.04 LTS linux-gcp +1 7.0.0-1008.8 USN-8593-1
Ubuntu 26.04 LTS linux-gke 7.0.0-1003.4 —
Ubuntu 26.04 LTS linux-ibm +1 7.0.0-1010.10 USN-8603-1, USN-8593-1
Ubuntu 26.04 LTS linux-nvidia 7.0.0-1016.16 USN-8663-1
Ubuntu 26.04 LTS linux-nvidia-bos 7.0.0-2016.16 USN-8664-1
Ubuntu 26.04 LTS linux-raspi 7.0.0-1015.15 USN-8618-1
Ubuntu 26.04 LTS linux-riscv +1 7.0.0-28.28.1 —
Ubuntu 24.04 LTS linux 6.8.0-139.139 USN-8729-1
Ubuntu 24.04 LTS linux-aws 6.8.0-1064.67 USN-8729-6
Ubuntu 24.04 LTS linux-azure-7.0 7.0.0-1014.14~24.04.1 USN-8728-2
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1065.72 —
Ubuntu 24.04 LTS linux-azure-fde-7.0 7.0.0-1013.13~24.04.1 —
Ubuntu 24.04 LTS linux-gcp +1 6.8.0-1067.75 USN-8761-1, USN-8729-1
Ubuntu 24.04 LTS linux-gcp-7.0 +1 7.0.0-1011.11~24.04.1 USN-8728-3, USN-8728-1
Ubuntu 24.04 LTS linux-gke 6.8.0-1062.70 USN-8729-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1049.53 USN-8729-1
Ubuntu 24.04 LTS linux-hwe-7.0 7.0.0-28.28~24.04.1 —
Ubuntu 24.04 LTS linux-ibm 6.8.0-1064.65 USN-8729-3
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-139.139.1 USN-8729-4
Ubuntu 24.04 LTS linux-nvidia 6.8.0-1062.65 USN-8729-1
Ubuntu 24.04 LTS linux-nvidia-7.0 7.0.0-1016.16~24.04.1 USN-8663-1
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1062.65.1 USN-8729-1
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1035.38 USN-8781-1
Ubuntu 24.04 LTS linux-oracle 6.8.0-1061.64 USN-8802-1
Ubuntu 24.04 LTS linux-raspi 6.8.0-1064.68 USN-8729-1
Ubuntu 24.04 LTS linux-riscv +28 No fix yet —
Ubuntu 24.04 LTS linux-riscv-7.0 7.0.0-28.28.1~24.04.3 —
Ubuntu 24.04 LTS linux-vmware 6.8.0-1008.8 —
Ubuntu 24.04 LTS linux-xilinx 6.8.0-1036.37 USN-8729-3
Ubuntu 22.04 LTS linux 5.15.0-186.196 USN-8575-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1112.119 USN-8575-2
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1064.67~22.04.1 USN-8729-6
Ubuntu 22.04 LTS linux-azure +1 5.15.0-1117.126 USN-8610-1, USN-8575-3
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1065.72~22.04.1 —
Ubuntu 22.04 LTS linux-gcp 5.15.0-1112.122 USN-8575-1
Ubuntu 22.04 LTS linux-gcp-6.8 +1 6.8.0-1067.75~22.04.1 USN-8761-3, USN-8729-3
Ubuntu 22.04 LTS linux-gke 5.15.0-1108.114 USN-8575-1
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1095.103 USN-8575-1
Ubuntu 22.04 LTS linux-hwe-6.8 6.8.0-149.149~22.04.1 USN-9066-1
Ubuntu 22.04 LTS linux-ibm 5.15.0-1106.110 USN-8575-2
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1066.67~22.04.1 USN-8906-1
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1107.113 USN-8620-4
Ubuntu 22.04 LTS linux-kvm 5.15.0-1104.109 USN-8575-1
Ubuntu 22.04 LTS linux-lowlatency 5.15.0-184.194 USN-8575-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-139.139.1~22.04.1 USN-8729-4
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1107.108 USN-8575-2
Ubuntu 22.04 LTS linux-nvidia-6.8 6.8.0-1062.65~22.04.1 USN-8729-1
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1064.66 USN-8576-2
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1053.53 USN-8576-2
Ubuntu 22.04 LTS linux-oracle 5.15.0-1109.115 USN-8575-3
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1061.64~22.04.1 USN-8802-1
Ubuntu 22.04 LTS linux-raspi 5.15.0-1106.109 USN-8668-2
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 22.04 LTS linux-riscv-6.8 6.8.0-139.139~22.04.1 —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1075.79 USN-8575-1
Show 12 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2053.55 USN-8729-2
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1059.60 USN-8729-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 +1 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1104.106 USN-8620-3
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1111.120 USN-8575-1
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1059.60~22.04.1 USN-8729-1
Ubuntu Pro FIPS 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1064.67+fips1 USN-8729-5
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-139.139+fips1 USN-8729-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips +1 6.8.0-1067.75+fips1 USN-8761-2, USN-8729-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1112.119+fips1 USN-8575-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1117.126+fips1 USN-8620-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-186.196+fips1 USN-8575-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1112.122+fips1 USN-8575-1
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-preview 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 20.04 LTS linux +10 No fix yet —
Ubuntu Pro 20.04 LTS linux-aws-5.15 5.15.0-1112.119~20.04.1 USN-8575-2
Ubuntu Pro 20.04 LTS linux-azure-5.15 5.15.0-1117.126~20.04.1 USN-8620-1
Ubuntu Pro 20.04 LTS linux-azure-fde-5.15 5.15.0-1117.126~20.04.2 USN-8620-1
Ubuntu Pro 20.04 LTS linux-gcp-5.15 5.15.0-1112.122~20.04.1 USN-8668-1
Ubuntu Pro 20.04 LTS linux-hwe-5.15 5.15.0-186.196~20.04.1 USN-8575-1
Ubuntu Pro 20.04 LTS linux-ibm-5.15 +1 5.15.0-1106.110~20.04.1 —
Ubuntu Pro 20.04 LTS linux-intel-iotg-5.15 5.15.0-1107.113~20.04.1 USN-8620-3
Ubuntu Pro 20.04 LTS linux-lowlatency-hwe-5.15 5.15.0-184.194~20.04.1 USN-8575-1
Ubuntu Pro 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1064.66~20.04.1 USN-8576-1
Ubuntu Pro 20.04 LTS linux-oracle-5.15 5.15.0-1109.115~20.04.1 USN-8620-1
Ubuntu Pro 18.04 LTS linux-aws-5.4 +6 No fix yet —
ReleasePackageFixed inAdvisory
RHEL 9 rv +75 5.14.0-687.53.1.el9_8 RHSA-2026:72623
RHEL 8 kernel-rt +12 4.18.0-553.170.1.rt7.511.el8_10 RHSA-2026:74132
RHEL 8 perf +26 4.18.0-553.170.1.el8_10 RHSA-2026:74133

AlmaLinux

Errata ↗
ReleasePackageFixed inAdvisory
AlmaLinux 9 rv +73 5.14.0-687.53.1.el9_8 ALSA-2026:72623
AlmaLinux 8 kernel-rt +9 4.18.0-553.170.1.rt7.511.el8_10 ALSA-2026:74132
AlmaLinux 8 perf +24 4.18.0-553.170.1.el8_10 ALSA-2026:74133

Rocky Linux

Errata ↗
ReleasePackageFixed inAdvisory
Rocky Linux 9 kernel 5.14.0-687.53.1.el9_8 RLSA-2026:72623
Rocky Linux 8 kernel 4.18.0-553.170.1.el8_10 RLSA-2026:74133
Rocky Linux 8 kernel-rt 4.18.0-553.170.1.rt7.511.el8_10 RLSA-2026:74132
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +7 6.4.0-150700.53.81.1 SUSE-SU-2026:4254-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.81.1.150700.17.45.1 SUSE-SU-2026:4254-1
Show 7 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 kernel-64kb +8 6.12.0-160000.38.1 SUSE-SU-2026:23902-1
SLES for SAP 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23902-1
SLES 16.0 kernel-64kb +8 6.12.0-160000.38.1 SUSE-SU-2026:23902-1, SUSE-SU-2026:23897-1
SLES 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23902-1
SLE Micro 6.2 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23887-1
SLE Micro 6.2 kernel-rt +5 6.12.0-160000.38.1 SUSE-SU-2026:23887-1, SUSE-SU-2026:23881-1
SLE Micro 6.1 kernel-default-base 6.4.0-52.1.21.34 SUSE-SU-2026:23529-1
SLE Micro 6.1 kernel-rt +4 6.4.0-52.1 SUSE-SU-2026:23529-1, SUSE-SU-2026:23528-1
SLE Micro 6.0 kernel-default-base 6.4.0-52.1.21.36 SUSE-SU-2026:23481-1
SLE Micro 6.0 kernel-rt +4 6.4.0-52.1 SUSE-SU-2026:23481-1, SUSE-SU-2026:23477-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.81.1 SUSE-SU-2026:4254-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7-RT_Update_20 1-150700.1.3.1 SUSE-SU-2026:4120-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_21 1-150700.15.3.1 SUSE-SU-2026:4254-1
SUSE Real Time Module 15 SP7 kernel-rt +2 6.4.0-150700.7.75.1 SUSE-SU-2026:4120-1
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.22 openSUSE-SU-2026:21910-1
openSUSE Leap 16.0 kernel-rt +11 6.12.0-160000.38.1 openSUSE-SU-2026:21910-1

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 rv +28 5.14.0-687.53.1.el9_8 ELSA-2026-72623
Oracle Linux 8 perf +19 4.18.0-553.170.1.el8_10 ELSA-2026-74133

Advisories 50

References