# CVE-2022-49888: arm64: entry: avoid kprobe recursion

> A kernel recursion issue in ARM64 debug handling can cause stack overflow and system crash when specific kprobes are enabled.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 May 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-49888, GHSA-w77p-v2rp-vmv8, UBUNTU-CVE-2022-49888

## What is CVE-2022-49888?

CVE-2022-49888 is a high-severity denial of service vulnerability in Linux kernel, published on 1 May 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:

arm64: entry: avoid kprobe recursion

The cortex_a76_erratum_1463225_debug_handler() function is called when
handling debug exceptions (and synchronous exceptions from BRK
instructions), and so is called when a probed function executes. If the
compiler does not inline cortex_a76_erratum_1463225_debug_handler(), it
can be probed.

If cortex_a76_erratum_1463225_debug_handler() is probed, any debug
exception or software breakpoint exception will result in recursive
exceptions leading to a stack overflow. This can be triggered with the
ftrace multiple_probes selftest, and as per the example splat below.

This is a regression caused by commit:

  6459b8469753e9fe ("arm64: entry: consolidate Cortex-A76 erratum 1463225 workaround")

... which removed the NOKPROBE_SYMBOL() annotation associated with the
function.

My intent was that cortex_a76_erratum_1463225_debug_handler() would be
inlined into its caller, el1_dbg(), which is marked noinstr and cannot
be probed. Mark cortex_a76_erratum_1463225_debug_handler() as
__always_inline to ensure this.

Example splat prior to this patch (with recursive entries elided):

| # echo p cortex_a76_erratum_1463225_debug_handler > /sys/kernel/debug/tracing/kprobe_events
| # echo p do_el0_svc >> /sys/kernel/debug/tracing/kprobe_events
| # echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable
| Insufficient stack space to handle exception!
| ESR: 0x0000000096000047 -- DABT (current EL)
| FAR: 0xffff800009cefff0
| Task stack:     [0xffff800009cf0000..0xffff800009cf4000]
| IRQ stack:      [0xffff800008000000..0xffff800008004000]
| Overflow stack: [0xffff00007fbc00f0..0xffff00007fbc10f0]
| CPU: 0 PID: 145 Comm: sh Not tainted 6.0.0 #2
| Hardware name: linux,dummy-virt (DT)
| pstate: 604003c5 (nZCv DAIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| pc : arm64_enter_el1_dbg+0x4/0x20
| lr : el1_dbg+0x24/0x5c
| sp : ffff800009cf0000
| x29: ffff800009cf0000 x28: ffff000002c74740 x27: 0000000000000000
| x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
| x23: 00000000604003c5 x22: ffff80000801745c x21: 0000aaaac95ac068
| x20: 00000000f2000004 x19: ffff800009cf0040 x18: 0000000000000000
| x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
| x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
| x11: 0000000000000010 x10: ffff800008c87190 x9 : ffff800008ca00d0
| x8 : 000000000000003c x7 : 0000000000000000 x6 : 0000000000000000
| x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000000043a4
| x2 : 00000000f2000004 x1 : 00000000f2000004 x0 : ffff800009cf0040
| Kernel panic - not syncing: kernel stack overflow
| CPU: 0 PID: 145 Comm: sh Not tainted 6.0.0 #2
| Hardware name: linux,dummy-virt (DT)
| Call trace:
|  dump_backtrace+0xe4/0x104
|  show_stack+0x18/0x4c
|  dump_stack_lvl+0x64/0x7c
|  dump_stack+0x18/0x38
|  panic+0x14c/0x338
|  test_taint+0x0/0x2c
|  panic_bad_stack+0x104/0x118
|  handle_bad_stack+0x34/0x48
|  __bad_stack+0x78/0x7c
|  arm64_enter_el1_dbg+0x4/0x20
|  el1h_64_sync_handler+0x40/0x98
|  el1h_64_sync+0x64/0x68
|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34
...
|  el1h_64_sync_handler+0x40/0x98
|  el1h_64_sync+0x64/0x68
|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34
...
|  el1h_64_sync_handler+0x40/0x98
|  el1h_64_sync+0x64/0x68
|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34
|  el1h_64_sync_handler+0x40/0x98
|  el1h_64_sync+0x64/0x68
|  do_el0_svc+0x0/0x28
|  el0t_64_sync_handler+0x84/0xf0
|  el0t_64_sync+0x18c/0x190
| Kernel Offset: disabled
| CPU features: 0x0080,00005021,19001080
| Memory Limit: none
| ---[ end Kernel panic - not syncing: kernel stack overflow ]---

With this patch, cortex_a76_erratum_1463225_debug_handler() is inlined
into el1_dbg(), and el1_dbg() cannot be probed:

| # echo p cortex_a76_erratum_1463225_debug_handler > /sys/kernel/debug/tracing/kprobe_events
| sh: write error: No such file or directory
| # grep -w cortex_a76_errat
---truncated---

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2022-49888?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49888?

Apply the vendor's patch.

## Is CVE-2022-49888 being exploited?

There is no known exploitation of CVE-2022-49888 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-49888 and fix it if it is affected.

What it is: CVE-2022-49888 is a high-severity denial of service vulnerability in Linux kernel, published on 1 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2022-49888 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2022-49888/ (Markdown: https://insights.sbomify.com/CVE-2022-49888/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49888
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49888
- OSV: https://osv.dev/vulnerability/CVE-2022-49888

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49888/
Summaries are generated and may contain mistakes; the official description above is the record.