Cloudanix VulnDB

CVE-2023-53752

None

CVSS

—

EPSS

0.1%

Published

Dec 8, 2025

CISA due date

—

Cloudanix analysis

Schedule a fix SSVC: Track

A flaw in the Linux kernel can let specially crafted network settings cause the system to crash when handling certain network traffic.

Exploitation
Local Privilege
Attacker needs
High Privilege
Complexity
Moderate
Impact
Denial Of Service
Component
OS kernel
Class
Memory Corruption
Remediation
Patch
Effort
Medium
Patch risk
Low

What it actually does

Integer overflow in kmalloc_size_roundup() when size exceeds 0x80000001 causes truncation of obj_size to zero in 32-bit variable, resulting in kmalloc(0) returning ZERO_SIZE_PTR that skb allocation paths do not handle, leading to invalid memory writes and crashes.

Why it matters to the business

Network interface configuration or traffic processing can trigger kernel crashes and system instability on affected Linux kernels, requiring reboots and causing downtime for network-dependent services.

How an attack unfolds

An attacker configures a network device with an MTU near 0x7fffffff or triggers IGMP packet processing paths that invoke skb allocation; this exercises the flawed kmalloc_reserve logic and produces a zero-sized allocation that leads to memory corruption during subsequent skb operations.

How to fix it

Upgrade the Linux kernel to version 6.1.54 or later; apply vendor-supplied patches that correct the size handling in kmalloc_reserve before the roundup and truncation occur.

How to confirm the fix worked

Confirm running kernel version is at least 6.1.54; attempt reproduction with large MTU settings in a test environment and verify absence of KASAN reports or crashes in skbuff allocation paths.

Typical attack path

  1. Identify or control a network interface on the target system
  2. Set netdev MTU to a value close to 0x7fffffff
  3. Trigger IGMPv3 or skb allocation routines via multicast or timer expiration
  4. Cause kernel to execute __alloc_skb with invalid pointer resulting in crash

How to detect it

Review kernel logs for KASAN reports or BUG entries referencing __alloc_skb, __build_skb_around, igmpv3_newpack, or igmp_ifc_timer_expire; search for crashes triggered after MTU changes.

What your security team should do

  • Apply kernel updates to 6.1.54 or newer on all affected systems without delay
  • Restrict unprivileged users from modifying network device MTU values via policy or capabilities
  • Monitor for kernel oops or panic logs involving skbuff and igmp functions

The record

In the Linux kernel, the following vulnerability has been resolved: net: deal with integer overflows in kmalloc_reserve() Blamed commit changed: ptr = kmalloc(size); if (ptr) size = ksize(ptr); size = kmalloc_size_roundup(size); ptr = kmalloc(size); This allowed various crash as reported by syzbot [1] and Kyle Zeng. Problem is that if @size is bigger than 0x80000001, kmalloc_size_roundup(size) returns 2^32. kmalloc_reserve() uses a 32bit variable (obj_size), so 2^32 is truncated to 0. kmalloc(0) returns ZERO_SIZE_PTR which is not handled by skb allocations. Following trace can be triggered if a netdev->mtu is set close to 0x7fffffff We might in the future limit netdev->mtu to more sensible limit (like KMALLOC_MAX_SIZE). This patch is based on a syzbot report, and also a report and tentative fix from Kyle Zeng. [1] BUG: KASAN: user-memory-access in __build_skb_around net/core/skbuff.c:294 [inline] BUG: KASAN: user-memory-access in __alloc_skb+0x3c4/0x6e8 net/core/skbuff.c:527 Write of size 32 at addr 00000000fffffd10 by task syz-executor.4/22554 CPU: 1 PID: 22554 Comm: syz-executor.4 Not tainted 6.1.39-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:279 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:286 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x120/0x1a0 lib/dump_stack.c:106 print_report+0xe4/0x4b4 mm/kasan/report.c:398 kasan_report+0x150/0x1ac mm/kasan/report.c:495 kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:189 memset+0x40/0x70 mm/kasan/shadow.c:44 __build_skb_around net/core/skbuff.c:294 [inline] __alloc_skb+0x3c4/0x6e8 net/core/skbuff.c:527 alloc_skb include/linux/skbuff.h:1316 [inline] igmpv3_newpack+0x104/0x1088 net/ipv4/igmp.c:359 add_grec+0x81c/0x1124 net/ipv4/igmp.c:534 igmpv3_send_cr net/ipv4/igmp.c:667 [inline] igmp_ifc_timer_expire+0x1b0/0x1008 net/ipv4/igmp.c:810 call_timer_fn+0x1c0/0x9f0 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers+0x54c/0x710 kernel/time/timer.c:1790 run_timer_softirq+0x28/0x4c kernel/time/timer.c:1803 _stext+0x380/0xfbc ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:79 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:891 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:84 invoke_softirq kernel/softirq.c:437 [inline] __irq_exit_rcu+0x1c0/0x4cc kernel/softirq.c:683 irq_exit_rcu+0x14/0x78 kernel/softirq.c:695 el0_interrupt+0x7c/0x2e0 arch/arm64/kernel/entry-common.c:717 __el0_irq_handler_common+0x18/0x24 arch/arm64/kernel/entry-common.c:724 el0t_64_irq_handler+0x10/0x1c arch/arm64/kernel/entry-common.c:729 el0t_64_irq+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Affected packages

Ecosystem Package Introduced Fixed
Linux Kernel 0 6.1.54
SUSE:Linux Enterprise High Availability Extension 15 SP6 kernel-default 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Live Patching 15 SP6 kernel-default 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_19 0 1-150600.13.3.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-64kb 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-default 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-default-base 0 6.4.0-150600.23.84.1.150600.12.38.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-docs 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-obs-build 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-source 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-syms 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-zfcpdump 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-default 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-default-base 0 6.4.0-150600.23.84.1.150600.12.38.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-docs 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-obs-build 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-source 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-syms 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 dtb-aarch64 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-64kb 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-debug 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-default 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-default-base 0 6.4.0-150600.23.84.1.150600.12.38.1
openSUSE:Leap 15.6 kernel-docs 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-kvmsmall 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-obs-build 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-obs-qa 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-source 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-syms 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-zfcpdump 0 6.4.0-150600.23.84.1

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