---
id: CVE-2026-98588
title: 'bpf, sockmap: Reject max_entries > INT_MAX in sock_map_alloc'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf, sockmap: Reject max_entries > INT_MAX in sock_map_alloc

  sock_map_alloc() only rejects max_entries == 0 and otherwise allows any
  u32 value.  sock_map_free() then w…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 <
    f4a73f49e256bd835368504462be3b57b03febff
  - >-
    Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 <
    c56191af3a578b9cc265fa3bd5fc0752c59c1781
  - >-
    Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 <
    909f761868fda329dc69130ef9eb5b5795bcdf00
  - >-
    Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 <
    cc70972ddbf0e3398f2f32624d31db78594d50d8
  - >-
    Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 <
    cea597519b9ca6d691c98d92460ead8ece2a07af
  - >-
    Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 <
    ba7d627dbc67d62df2fa66d7b41e743c3ace0ec8
  - >-
    Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 <
    814a81c842bd88f6bd8a4ce550d560df071a5d03
  - Linux 5.11
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:19:00.934Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98588'
references:
  - url: 'https://git.kernel.org/stable/c/f4a73f49e256bd835368504462be3b57b03febff'
  - url: 'https://git.kernel.org/stable/c/c56191af3a578b9cc265fa3bd5fc0752c59c1781'
  - url: 'https://git.kernel.org/stable/c/909f761868fda329dc69130ef9eb5b5795bcdf00'
  - url: 'https://git.kernel.org/stable/c/cc70972ddbf0e3398f2f32624d31db78594d50d8'
  - url: 'https://git.kernel.org/stable/c/cea597519b9ca6d691c98d92460ead8ece2a07af'
  - url: 'https://git.kernel.org/stable/c/ba7d627dbc67d62df2fa66d7b41e743c3ace0ec8'
  - url: 'https://git.kernel.org/stable/c/814a81c842bd88f6bd8a4ce550d560df071a5d03'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.252Z'
---

## Overview

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

bpf, sockmap: Reject max_entries > INT_MAX in sock_map_alloc

sock_map_alloc() only rejects max_entries == 0 and otherwise allows any
u32 value.  sock_map_free() then walks the sks[] array with a signed int
iterator:

	int i;
	for (i = 0; i < stab->map.max_entries; i++)
		struct sock **psk = &stab->sks[i];

When a SOCKMAP is created with max_entries = 0xffffffff (UINT_MAX), the
allocation of 32 GiB can succeed on large-memory hosts.  During free the
counter reaches 0x80000000, wraps to INT_MIN, is sign-extended by movslq
and turned into a ~16 GiB negative offset from stab->sks, pointing far
below the allocation.

The faulting access is an xchg() write in sock_map_free().  Without
KASAN, the same out-of-bounds write can fault on an unmapped vmalloc page
or corrupt an unrelated allocation if that vmalloc address is populated.
On a KASAN kernel with CONFIG_KASAN_VMALLOC=y, the shadow check for that
address hits an unmapped shadow page and oopses first:

  BUG: unable to handle page fault for address: fffff521b59c5a00
  RIP: 0010:kasan_check_range+0x107/0x190
  Call Trace:
   sock_map_free+0x93/0x190
   map_create+0x68d/0xb30
   __sys_bpf+0x21e/0x2e70

Vmcore confirmed stab->map.max_entries == 0xffffffff, stab->sks ==
0xffffc911ace2d000, and the faulting address sks + (s64)INT_MIN * 8
exactly at 0xffffc90dace2d000.  The same buggy path is reached on the
normal close()/bpf_map_free_deferred() path whenever such a map is
destroyed.

sock_map_alloc() used to bound its allocation size through
bpf_map_charge_init(), but the bound was dropped when rlimit-based memory
accounting was removed.  Reject max_entries > INT_MAX at creation time so
the signed iterator in sock_map_free() never sees a value that would
overflow.

Triggered by syzkaller and reproduced on both a 6.6-based KASAN kernel
and the upstream v7.3-rc2 kernel.

## Affected

- `Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 < f4a73f49e256bd835368504462be3b57b03febff`
- `Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 < c56191af3a578b9cc265fa3bd5fc0752c59c1781`
- `Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 < 909f761868fda329dc69130ef9eb5b5795bcdf00`
- `Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 < cc70972ddbf0e3398f2f32624d31db78594d50d8`
- `Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 < cea597519b9ca6d691c98d92460ead8ece2a07af`
- `Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 < ba7d627dbc67d62df2fa66d7b41e743c3ace0ec8`
- `Linux >= 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1 < 814a81c842bd88f6bd8a4ce550d560df071a5d03`
- `Linux 5.11`

## Remediation

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