---
id: CVE-2026-98801
title: 'net: restrict SO_RESERVE_MEM to TCP sockets and cap max value'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: restrict SO_RESERVE_MEM to TCP sockets and cap max value

  Commit 2bb2f5fb21b0 ("net: add new socket option SO_RESERVE_MEM") and
  commit d00c8ee31729 ("net: fix poss…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 <
    492e04f9a00f3cc88a1f6899417b10f3019a624e
  - >-
    Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 <
    5069ce898148bd799395c5a464e006cbb840f188
  - >-
    Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 <
    a467b05b201b5c26be52ed3081992fa9c0387648
  - >-
    Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 <
    37e02c42a00be692c06343e11779aadc45f45971
  - Linux 5.16
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:48:47.171Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98801'
references:
  - url: 'https://git.kernel.org/stable/c/492e04f9a00f3cc88a1f6899417b10f3019a624e'
  - url: 'https://git.kernel.org/stable/c/5069ce898148bd799395c5a464e006cbb840f188'
  - url: 'https://git.kernel.org/stable/c/a467b05b201b5c26be52ed3081992fa9c0387648'
  - url: 'https://git.kernel.org/stable/c/37e02c42a00be692c06343e11779aadc45f45971'
tags:
  - cve.org
ingestedAt: '2026-10-18T16:47:32.481Z'
---

## Overview

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

net: restrict SO_RESERVE_MEM to TCP sockets and cap max value

Commit 2bb2f5fb21b0 ("net: add new socket option SO_RESERVE_MEM") and
commit d00c8ee31729 ("net: fix possible NULL deref in sock_reserve_memory")
only checked sk_has_account(sk), which is true for both TCP and UDP
sockets.

However, SO_RESERVE_MEM and sk_unused_reserved_mem() are currently only
supported by TCP:
- On UDP sockets, sk->sk_forward_alloc is protected by
  sk->sk_receive_queue.lock, whereas sock_reserve_memory() and
  sock_release_reserved_memory() only acquire lock_sock(sk). Concurrent
  UDP packet reception/release and setsockopt(SO_RESERVE_MEM) corrupt
  sk_forward_alloc and memcg accounting.
- udp_rmem_release() reclaims excess sk_forward_alloc without
  accounting for sk_unused_reserved_mem(sk).

Restrict sock_reserve_memory() to TCP sockets (sk_is_tcp(sk)) for now.
Supporting SO_RESERVE_MEM for UDP (acquiring sk_receive_queue.lock and
honoring sk_unused_reserved_mem() in udp_rmem_release()) can be done in
a future net-next series if needed.

In addition, reject val > SZ_1G with -EINVAL in
sk_setsockopt(SO_RESERVE_MEM). Without an upper bound, values near
INT_MAX cause sk_mem_pages(delta) and (pages << PAGE_SHIFT) to overflow
32-bit signed int, corrupting sk->sk_forward_alloc and
sk->sk_reserved_mem. Using a page-aligned cap (SZ_1G) ensures that the
page-rounded sk->sk_reserved_mem reported by getsockopt(SO_RESERVE_MEM)
can always be passed back to setsockopt(SO_RESERVE_MEM).

## Affected

- `Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 492e04f9a00f3cc88a1f6899417b10f3019a624e`
- `Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 5069ce898148bd799395c5a464e006cbb840f188`
- `Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < a467b05b201b5c26be52ed3081992fa9c0387648`
- `Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 37e02c42a00be692c06343e11779aadc45f45971`
- `Linux 5.16`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.