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CVE-2023-53752: net: deal with integer overflows in kmalloc_reserve()

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

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2023-53752 is a Linux kernel networking memory allocation bug. An extremely large network MTU can cause an integer overflow, leading kernel socket-buffer allocation code to operate on an invalid zero-size allocation and crash. The supplied sources show a resolved kernel bug, not confirmed real-world exploitation.

Executive priority

Treat this as a patch-management priority for Linux infrastructure, especially systems with delegated network configuration. It is not KEV-listed in the supplied bundle, so urgency is below confirmed exploited kernel flaws, but kernel crash risk justifies scheduled remediation.

Technical view

kmalloc_reserve() rounded very large sizes to 2^32, then stored the result in a 32-bit obj_size, truncating it to zero. kmalloc(0) returns ZERO_SIZE_PTR, which skb allocation paths did not handle. The reported crash path involves net/core/skbuff.c and IGMP code when netdev->mtu is near 0x7fffffff.

Likely exposure

Exposure is most relevant to Linux systems running affected kernel versions where network device MTU values can be set to extremely large values. The bundle lists Linux as affected across 6.2, 6.1.54, 6.4.16, 6.5.3, and 6.6-era version data, with stable fix commits referenced.

Exploitation context

The evidence is from syzbot and a researcher report, with a kernel crash trace. The source bundle marks KEV as false and provides no cited evidence of active exploitation, public weaponization, privilege impact, or remote exploitation.

Researcher notes

Key validation points are the kmalloc_reserve() integer truncation, ZERO_SIZE_PTR handling in skb allocation, and the large-MTU trigger condition. The bundle lacks CVSS, CWE, exploitability assessment, and distro-specific affected package mappings, so conclusions should remain conservative.

Mitigation direction

  • Update to a Linux kernel containing the referenced stable fixes.
  • Check distribution vendor advisories for backported kernel packages.
  • Avoid unusually large network MTU settings until patched.
  • Restrict who can change network interface MTU values.
  • Prioritize exposed multi-tenant or container hosts where network settings may be delegated.

Validation and detection

  • Inventory running Linux kernel versions across servers and appliances.
  • Confirm installed kernels include the referenced stable commits or vendor backports.
  • Review network configuration management for extreme MTU values.
  • Verify no internal alerting assumes confirmed active exploitation.
  • Track vendor guidance because CVSS and CWE details are absent.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2023-53752 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
5Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux0dbc898f5917c5a3bec6be19d9f5469cbc351a7d, 12d6c1d3a2ad0c199ec57c201cdc71e8e157a232, 12d6c1d3a2ad0c199ec57c201cdc71e8e157a232, 12d6c1d3a2ad0c199ec57c201cdc71e8e157a232, 6.1.31unaffected
LinuxLinux6.2, 0, 6.1.54, 6.4.16, 6.5.3, 6.6affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.