CVE Vulnerabilities

CVE-2025-38463

Published: Jul 25, 2025 | Modified: Jul 29, 2025
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
RedHat/V2
RedHat/V3
8.1 IMPORTANT
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Ubuntu
MEDIUM

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

tcp: Correct signedness in skb remaining space calculation

Syzkaller reported a bug 1 where sk->sk_forward_alloc can overflow.

When we send data, if an skb exists at the tail of the write queue, the kernel will attempt to append the new data to that skb. However, the code that checks for available space in the skb is flawed:

copy = size_goal - skb->len

The types of the variables involved are:

copy: ssize_t (s64 on 64-bit systems) size_goal: int skb->len: unsigned int

Due to Cs type promotion rules, the signed size_goal is converted to an unsigned int to match skb->len before the subtraction. The result is an unsigned int.

When this unsigned int result is then assigned to the s64 copy variable, it is zero-extended, preserving its non-negative value. Consequently, copy is always >= 0.

Assume we are sending 2GB of data and size_goal has been adjusted to a value smaller than skb->len. The subtraction will result in copy holding a very large positive integer. In the subsequent logic, this large value is used to update sk->sk_forward_alloc, which can easily cause it to overflow.

The syzkaller reproducer uses TCP_REPAIR to reliably create this condition. However, this can also occur in real-world scenarios. The tcp_bound_to_half_wnd() function can also reduce size_goal to a small value. This would cause the subsequent tcp_wmem_schedule() to set sk->sk_forward_alloc to a value close to INT_MAX. Further memory allocation requests would then cause sk_forward_alloc to wrap around and become negative.

Affected Software

Name Vendor Start Version End Version
Linux Ubuntu devel *
Linux Ubuntu noble *
Linux Ubuntu plucky *
Linux Ubuntu upstream *
Linux-allwinner-5.19 Ubuntu jammy *
Linux-allwinner-5.19 Ubuntu upstream *
Linux-aws Ubuntu devel *
Linux-aws Ubuntu noble *
Linux-aws Ubuntu plucky *
Linux-aws Ubuntu upstream *
Linux-aws-5.0 Ubuntu bionic *
Linux-aws-5.0 Ubuntu esm-infra/bionic *
Linux-aws-5.0 Ubuntu upstream *
Linux-aws-5.11 Ubuntu esm-infra/focal *
Linux-aws-5.11 Ubuntu focal *
Linux-aws-5.11 Ubuntu upstream *
Linux-aws-5.13 Ubuntu esm-infra/focal *
Linux-aws-5.13 Ubuntu focal *
Linux-aws-5.13 Ubuntu upstream *
Linux-aws-5.15 Ubuntu upstream *
Linux-aws-5.19 Ubuntu jammy *
Linux-aws-5.19 Ubuntu upstream *
Linux-aws-5.3 Ubuntu bionic *
Linux-aws-5.3 Ubuntu esm-infra/bionic *
Linux-aws-5.3 Ubuntu upstream *
Linux-aws-5.4 Ubuntu upstream *
Linux-aws-5.8 Ubuntu esm-infra/focal *
Linux-aws-5.8 Ubuntu focal *
Linux-aws-5.8 Ubuntu upstream *
Linux-aws-6.14 Ubuntu noble *
Linux-aws-6.14 Ubuntu upstream *
Linux-aws-6.2 Ubuntu jammy *
Linux-aws-6.2 Ubuntu upstream *
Linux-aws-6.5 Ubuntu jammy *
Linux-aws-6.5 Ubuntu upstream *
Linux-aws-6.8 Ubuntu jammy *
Linux-aws-6.8 Ubuntu upstream *
Linux-aws-fips Ubuntu trusty *
Linux-aws-fips Ubuntu upstream *
Linux-aws-fips Ubuntu xenial *
Linux-aws-hwe Ubuntu upstream *
Linux-azure Ubuntu bionic *
Linux-azure Ubuntu devel *
Linux-azure Ubuntu esm-infra/bionic *
Linux-azure Ubuntu noble *
Linux-azure Ubuntu plucky *
Linux-azure Ubuntu upstream *
Linux-azure-4.15 Ubuntu upstream *
Linux-azure-5.11 Ubuntu esm-infra/focal *
Linux-azure-5.11 Ubuntu focal *
Linux-azure-5.11 Ubuntu upstream *
Linux-azure-5.13 Ubuntu esm-infra/focal *
Linux-azure-5.13 Ubuntu focal *
Linux-azure-5.13 Ubuntu upstream *
Linux-azure-5.15 Ubuntu upstream *
Linux-azure-5.19 Ubuntu jammy *
Linux-azure-5.19 Ubuntu upstream *
Linux-azure-5.3 Ubuntu bionic *
Linux-azure-5.3 Ubuntu esm-infra/bionic *
Linux-azure-5.3 Ubuntu upstream *
Linux-azure-5.4 Ubuntu upstream *
Linux-azure-5.8 Ubuntu esm-infra/focal *
Linux-azure-5.8 Ubuntu focal *
Linux-azure-5.8 Ubuntu upstream *
Linux-azure-6.11 Ubuntu noble *
Linux-azure-6.11 Ubuntu upstream *
Linux-azure-6.2 Ubuntu jammy *
Linux-azure-6.2 Ubuntu upstream *
Linux-azure-6.5 Ubuntu jammy *
Linux-azure-6.5 Ubuntu upstream *
Linux-azure-6.8 Ubuntu jammy *
Linux-azure-6.8 Ubuntu upstream *
Linux-azure-edge Ubuntu bionic *
Linux-azure-edge Ubuntu esm-infra/bionic *
Linux-azure-edge Ubuntu upstream *
Linux-azure-fde Ubuntu esm-infra/focal *
Linux-azure-fde Ubuntu focal *
Linux-azure-fde Ubuntu upstream *
Linux-azure-fde-5.15 Ubuntu upstream *
Linux-azure-fde-5.19 Ubuntu jammy *
Linux-azure-fde-5.19 Ubuntu upstream *
Linux-azure-fde-6.2 Ubuntu jammy *
Linux-azure-fde-6.2 Ubuntu upstream *
Linux-azure-fips Ubuntu trusty *
Linux-azure-fips Ubuntu upstream *
Linux-azure-fips Ubuntu xenial *
Linux-azure-nvidia Ubuntu noble *
Linux-azure-nvidia Ubuntu upstream *
Linux-bluefield Ubuntu upstream *
Linux-fips Ubuntu upstream *
Linux-gcp Ubuntu bionic *
Linux-gcp Ubuntu devel *
Linux-gcp Ubuntu esm-infra/bionic *
Linux-gcp Ubuntu noble *
Linux-gcp Ubuntu plucky *
Linux-gcp Ubuntu upstream *
Linux-gcp-4.15 Ubuntu upstream *
Linux-gcp-5.11 Ubuntu esm-infra/focal *
Linux-gcp-5.11 Ubuntu focal *
Linux-gcp-5.11 Ubuntu upstream *
Linux-gcp-5.13 Ubuntu esm-infra/focal *
Linux-gcp-5.13 Ubuntu focal *
Linux-gcp-5.13 Ubuntu upstream *
Linux-gcp-5.15 Ubuntu upstream *
Linux-gcp-5.19 Ubuntu jammy *
Linux-gcp-5.19 Ubuntu upstream *
Linux-gcp-5.3 Ubuntu bionic *
Linux-gcp-5.3 Ubuntu esm-infra/bionic *
Linux-gcp-5.3 Ubuntu upstream *
Linux-gcp-5.4 Ubuntu upstream *
Linux-gcp-5.8 Ubuntu esm-infra/focal *
Linux-gcp-5.8 Ubuntu focal *
Linux-gcp-5.8 Ubuntu upstream *
Linux-gcp-6.11 Ubuntu noble *
Linux-gcp-6.11 Ubuntu upstream *
Linux-gcp-6.14 Ubuntu noble *
Linux-gcp-6.14 Ubuntu upstream *
Linux-gcp-6.2 Ubuntu jammy *
Linux-gcp-6.2 Ubuntu upstream *
Linux-gcp-6.5 Ubuntu jammy *
Linux-gcp-6.5 Ubuntu upstream *
Linux-gcp-6.8 Ubuntu jammy *
Linux-gcp-6.8 Ubuntu upstream *
Linux-gcp-fips Ubuntu trusty *
Linux-gcp-fips Ubuntu upstream *
Linux-gcp-fips Ubuntu xenial *
Linux-gke Ubuntu esm-infra/focal *
Linux-gke Ubuntu focal *
Linux-gke Ubuntu noble *
Linux-gke Ubuntu upstream *
Linux-gke Ubuntu xenial *
Linux-gke-4.15 Ubuntu bionic *
Linux-gke-4.15 Ubuntu esm-infra/bionic *
Linux-gke-4.15 Ubuntu upstream *
Linux-gke-5.15 Ubuntu esm-infra/focal *
Linux-gke-5.15 Ubuntu focal *
Linux-gke-5.15 Ubuntu upstream *
Linux-gke-5.4 Ubuntu bionic *
Linux-gke-5.4 Ubuntu esm-infra/bionic *
Linux-gke-5.4 Ubuntu upstream *
Linux-gkeop Ubuntu esm-infra/focal *
Linux-gkeop Ubuntu focal *
Linux-gkeop Ubuntu noble *
Linux-gkeop Ubuntu upstream *
Linux-gkeop-5.15 Ubuntu esm-infra/focal *
Linux-gkeop-5.15 Ubuntu focal *
Linux-gkeop-5.15 Ubuntu upstream *
Linux-gkeop-5.4 Ubuntu bionic *
Linux-gkeop-5.4 Ubuntu esm-infra/bionic *
Linux-gkeop-5.4 Ubuntu upstream *
Linux-hwe Ubuntu bionic *
Linux-hwe Ubuntu esm-infra/bionic *
Linux-hwe Ubuntu upstream *
Linux-hwe-5.11 Ubuntu esm-infra/focal *
Linux-hwe-5.11 Ubuntu focal *
Linux-hwe-5.11 Ubuntu upstream *
Linux-hwe-5.13 Ubuntu esm-infra/focal *
Linux-hwe-5.13 Ubuntu focal *
Linux-hwe-5.13 Ubuntu upstream *
Linux-hwe-5.15 Ubuntu upstream *
Linux-hwe-5.19 Ubuntu jammy *
Linux-hwe-5.19 Ubuntu upstream *
Linux-hwe-5.4 Ubuntu upstream *
Linux-hwe-5.8 Ubuntu esm-infra/focal *
Linux-hwe-5.8 Ubuntu focal *
Linux-hwe-5.8 Ubuntu upstream *
Linux-hwe-6.11 Ubuntu noble *
Linux-hwe-6.11 Ubuntu upstream *
Linux-hwe-6.14 Ubuntu noble *
Linux-hwe-6.14 Ubuntu upstream *
Linux-hwe-6.2 Ubuntu jammy *
Linux-hwe-6.2 Ubuntu upstream *
Linux-hwe-6.5 Ubuntu jammy *
Linux-hwe-6.5 Ubuntu upstream *
Linux-hwe-6.8 Ubuntu jammy *
Linux-hwe-6.8 Ubuntu upstream *
Linux-hwe-edge Ubuntu bionic *
Linux-hwe-edge Ubuntu esm-infra/bionic *
Linux-hwe-edge Ubuntu esm-infra/xenial *
Linux-hwe-edge Ubuntu upstream *
Linux-hwe-edge Ubuntu xenial *
Linux-ibm Ubuntu noble *
Linux-ibm Ubuntu upstream *
Linux-ibm-5.15 Ubuntu upstream *
Linux-ibm-5.4 Ubuntu upstream *
Linux-ibm-6.8 Ubuntu jammy *
Linux-ibm-6.8 Ubuntu upstream *
Linux-intel Ubuntu noble *
Linux-intel Ubuntu upstream *
Linux-intel-5.13 Ubuntu esm-infra/focal *
Linux-intel-5.13 Ubuntu focal *
Linux-intel-5.13 Ubuntu upstream *
Linux-intel-iot-realtime Ubuntu jammy *
Linux-intel-iot-realtime Ubuntu upstream *
Linux-intel-iotg Ubuntu upstream *
Linux-intel-iotg-5.15 Ubuntu upstream *
Linux-iot Ubuntu upstream *
Linux-kvm Ubuntu upstream *
Linux-lowlatency Ubuntu noble *
Linux-lowlatency Ubuntu upstream *
Linux-lowlatency-hwe-5.15 Ubuntu upstream *
Linux-lowlatency-hwe-5.19 Ubuntu jammy *
Linux-lowlatency-hwe-5.19 Ubuntu upstream *
Linux-lowlatency-hwe-6.11 Ubuntu noble *
Linux-lowlatency-hwe-6.11 Ubuntu upstream *
Linux-lowlatency-hwe-6.2 Ubuntu jammy *
Linux-lowlatency-hwe-6.2 Ubuntu upstream *
Linux-lowlatency-hwe-6.5 Ubuntu jammy *
Linux-lowlatency-hwe-6.5 Ubuntu upstream *
Linux-lowlatency-hwe-6.8 Ubuntu jammy *
Linux-lowlatency-hwe-6.8 Ubuntu upstream *
Linux-lts-xenial Ubuntu upstream *
Linux-nvidia Ubuntu noble *
Linux-nvidia Ubuntu upstream *
Linux-nvidia-6.11 Ubuntu noble *
Linux-nvidia-6.11 Ubuntu upstream *
Linux-nvidia-6.2 Ubuntu jammy *
Linux-nvidia-6.2 Ubuntu upstream *
Linux-nvidia-6.5 Ubuntu jammy *
Linux-nvidia-6.5 Ubuntu upstream *
Linux-nvidia-6.8 Ubuntu jammy *
Linux-nvidia-6.8 Ubuntu upstream *
Linux-nvidia-lowlatency Ubuntu noble *
Linux-nvidia-lowlatency Ubuntu upstream *
Linux-nvidia-tegra Ubuntu noble *
Linux-nvidia-tegra Ubuntu upstream *
Linux-nvidia-tegra-5.15 Ubuntu upstream *
Linux-nvidia-tegra-igx Ubuntu upstream *
Linux-oem Ubuntu bionic *
Linux-oem Ubuntu esm-infra/bionic *
Linux-oem Ubuntu upstream *
Linux-oem Ubuntu xenial *
Linux-oem-5.10 Ubuntu esm-infra/focal *
Linux-oem-5.10 Ubuntu focal *
Linux-oem-5.10 Ubuntu upstream *
Linux-oem-5.13 Ubuntu esm-infra/focal *
Linux-oem-5.13 Ubuntu focal *
Linux-oem-5.13 Ubuntu upstream *
Linux-oem-5.14 Ubuntu esm-infra/focal *
Linux-oem-5.14 Ubuntu focal *
Linux-oem-5.14 Ubuntu upstream *
Linux-oem-5.17 Ubuntu jammy *
Linux-oem-5.17 Ubuntu upstream *
Linux-oem-5.6 Ubuntu esm-infra/focal *
Linux-oem-5.6 Ubuntu focal *
Linux-oem-5.6 Ubuntu upstream *
Linux-oem-6.0 Ubuntu jammy *
Linux-oem-6.0 Ubuntu upstream *
Linux-oem-6.1 Ubuntu jammy *
Linux-oem-6.1 Ubuntu upstream *
Linux-oem-6.11 Ubuntu noble *
Linux-oem-6.11 Ubuntu upstream *
Linux-oem-6.14 Ubuntu noble *
Linux-oem-6.14 Ubuntu upstream *
Linux-oem-6.5 Ubuntu jammy *
Linux-oem-6.5 Ubuntu upstream *
Linux-oem-6.8 Ubuntu noble *
Linux-oem-6.8 Ubuntu upstream *
Linux-oracle Ubuntu devel *
Linux-oracle Ubuntu noble *
Linux-oracle Ubuntu plucky *
Linux-oracle Ubuntu upstream *
Linux-oracle-5.0 Ubuntu bionic *
Linux-oracle-5.0 Ubuntu esm-infra/bionic *
Linux-oracle-5.0 Ubuntu upstream *
Linux-oracle-5.11 Ubuntu esm-infra/focal *
Linux-oracle-5.11 Ubuntu focal *
Linux-oracle-5.11 Ubuntu upstream *
Linux-oracle-5.13 Ubuntu esm-infra/focal *
Linux-oracle-5.13 Ubuntu focal *
Linux-oracle-5.13 Ubuntu upstream *
Linux-oracle-5.15 Ubuntu upstream *
Linux-oracle-5.3 Ubuntu bionic *
Linux-oracle-5.3 Ubuntu esm-infra/bionic *
Linux-oracle-5.3 Ubuntu upstream *
Linux-oracle-5.4 Ubuntu upstream *
Linux-oracle-5.8 Ubuntu esm-infra/focal *
Linux-oracle-5.8 Ubuntu focal *
Linux-oracle-5.8 Ubuntu upstream *
Linux-oracle-6.14 Ubuntu noble *
Linux-oracle-6.14 Ubuntu upstream *
Linux-oracle-6.5 Ubuntu jammy *
Linux-oracle-6.5 Ubuntu upstream *
Linux-oracle-6.8 Ubuntu jammy *
Linux-oracle-6.8 Ubuntu upstream *
Linux-raspi Ubuntu devel *
Linux-raspi Ubuntu noble *
Linux-raspi Ubuntu plucky *
Linux-raspi Ubuntu upstream *
Linux-raspi-5.4 Ubuntu upstream *
Linux-raspi-realtime Ubuntu noble *
Linux-raspi-realtime Ubuntu realtime/noble *
Linux-raspi-realtime Ubuntu upstream *
Linux-raspi2 Ubuntu bionic *
Linux-raspi2 Ubuntu esm-infra/focal *
Linux-raspi2 Ubuntu focal *
Linux-raspi2 Ubuntu upstream *
Linux-raspi2 Ubuntu xenial *
Linux-realtime Ubuntu devel *
Linux-realtime Ubuntu jammy *
Linux-realtime Ubuntu noble *
Linux-realtime Ubuntu plucky *
Linux-realtime Ubuntu realtime/noble *
Linux-realtime Ubuntu upstream *
Linux-riscv Ubuntu devel *
Linux-riscv Ubuntu esm-infra/focal *
Linux-riscv Ubuntu focal *
Linux-riscv Ubuntu jammy *
Linux-riscv Ubuntu noble *
Linux-riscv Ubuntu plucky *
Linux-riscv Ubuntu upstream *
Linux-riscv-5.11 Ubuntu esm-infra/focal *
Linux-riscv-5.11 Ubuntu focal *
Linux-riscv-5.11 Ubuntu upstream *
Linux-riscv-5.15 Ubuntu upstream *
Linux-riscv-5.19 Ubuntu jammy *
Linux-riscv-5.19 Ubuntu upstream *
Linux-riscv-5.8 Ubuntu esm-infra/focal *
Linux-riscv-5.8 Ubuntu focal *
Linux-riscv-5.8 Ubuntu upstream *
Linux-riscv-6.14 Ubuntu noble *
Linux-riscv-6.14 Ubuntu upstream *
Linux-riscv-6.5 Ubuntu jammy *
Linux-riscv-6.5 Ubuntu upstream *
Linux-riscv-6.8 Ubuntu jammy *
Linux-riscv-6.8 Ubuntu upstream *
Linux-starfive-5.19 Ubuntu jammy *
Linux-starfive-5.19 Ubuntu upstream *
Linux-starfive-6.2 Ubuntu jammy *
Linux-starfive-6.2 Ubuntu upstream *
Linux-starfive-6.5 Ubuntu jammy *
Linux-starfive-6.5 Ubuntu upstream *
Linux-xilinx-zynqmp Ubuntu upstream *

References