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

What is CVE-2023-53752?

CVE-2023-53752 is a high-severity vulnerability in Linux, published on 8 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

Which versions are affected by CVE-2023-53752?

How do I fix CVE-2023-53752?

Apply the vendor's patch.

Is CVE-2023-53752 being exploited?

There is no known exploitation of CVE-2023-53752 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2023-53752, DEBIAN-CVE-2023-53752, GHSA-5g3x-gjgm-77rp, UBUNTU-CVE-2023-53752.