# CVE-2022-49228: bpf: Fix a btf decl_tag bug when tagging a function

> A null pointer dereference in the Linux kernel BPF subsystem allows local attackers to cause a system crash via crafted BTF data.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 26 Feb 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-49228, GHSA-xx7j-2fqw-vv47, UBUNTU-CVE-2022-49228

## What is CVE-2022-49228?

CVE-2022-49228 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 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:

bpf: Fix a btf decl_tag bug when tagging a function

syzbot reported a btf decl_tag bug with stack trace below:

  general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
  CPU: 0 PID: 3592 Comm: syz-executor914 Not tainted 5.16.0-syzkaller-11424-gb7892f7d5cb2 #0
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  RIP: 0010:btf_type_vlen include/linux/btf.h:231 [inline]
  RIP: 0010:btf_decl_tag_resolve+0x83e/0xaa0 kernel/bpf/btf.c:3910
  ...
  Call Trace:
   <TASK>
   btf_resolve+0x251/0x1020 kernel/bpf/btf.c:4198
   btf_check_all_types kernel/bpf/btf.c:4239 [inline]
   btf_parse_type_sec kernel/bpf/btf.c:4280 [inline]
   btf_parse kernel/bpf/btf.c:4513 [inline]
   btf_new_fd+0x19fe/0x2370 kernel/bpf/btf.c:6047
   bpf_btf_load kernel/bpf/syscall.c:4039 [inline]
   __sys_bpf+0x1cbb/0x5970 kernel/bpf/syscall.c:4679
   __do_sys_bpf kernel/bpf/syscall.c:4738 [inline]
   __se_sys_bpf kernel/bpf/syscall.c:4736 [inline]
   __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4736
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

The kasan error is triggered with an illegal BTF like below:
   type 0: void
   type 1: int
   type 2: decl_tag to func type 3
   type 3: func to func_proto type 8
The total number of types is 4 and the type 3 is illegal
since its func_proto type is out of range.

Currently, the target type of decl_tag can be struct/union, var or func.
Both struct/union and var implemented their own 'resolve' callback functions
and hence handled properly in kernel.
But func type doesn't have 'resolve' callback function. When
btf_decl_tag_resolve() tries to check func type, it tries to get
vlen of its func_proto type, which triggered the above kasan error.

To fix the issue, btf_decl_tag_resolve() needs to do btf_func_check()
before trying to accessing func_proto type.
In the current implementation, func type is checked with
btf_func_check() in the main checking function btf_check_all_types().
To fix the above kasan issue, let us implement 'resolve' callback
func type properly. The 'resolve' callback will be also called
in btf_check_all_types() for func types.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2022-49228?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49228?

Apply the vendor's patch.

## Is CVE-2022-49228 being exploited?

There is no known exploitation of CVE-2022-49228 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-2022-49228 and fix it if it is affected.

What it is: CVE-2022-49228 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 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-2022-49228 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-2022-49228/ (Markdown: https://insights.sbomify.com/CVE-2022-49228/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49228
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49228
- OSV: https://osv.dev/vulnerability/CVE-2022-49228

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49228/
Summaries are generated and may contain mistakes; the official description above is the record.