# CVE-2024-50254: bpf: Free dynamically allocated bits in bpf_iter_bits_destroy()

> A memory leak in the Linux kernel BPF subsystem can lead to resource exhaustion and denial of service.

- **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:** 9 Nov 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2024-50254, DEBIAN-CVE-2024-50254, GHSA-c7cg-c752-q6q2, UBUNTU-CVE-2024-50254

## What is CVE-2024-50254?

CVE-2024-50254 is a medium-severity memory corruption vulnerability in Linux kernel, published on 9 Nov 2024. 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: Free dynamically allocated bits in bpf_iter_bits_destroy()

bpf_iter_bits_destroy() uses "kit->nr_bits <= 64" to check whether the
bits are dynamically allocated. However, the check is incorrect and may
cause a kmemleak as shown below:

unreferenced object 0xffff88812628c8c0 (size 32):
  comm "swapper/0", pid 1, jiffies 4294727320
  hex dump (first 32 bytes):
	b0 c1 55 f5 81 88 ff ff f0 f0 f0 f0 f0 f0 f0 f0  ..U...........
	f0 f0 f0 f0 f0 f0 f0 f0 00 00 00 00 00 00 00 00  ..............
  backtrace (crc 781e32cc):
	[<00000000c452b4ab>] kmemleak_alloc+0x4b/0x80
	[<0000000004e09f80>] __kmalloc_node_noprof+0x480/0x5c0
	[<00000000597124d6>] __alloc.isra.0+0x89/0xb0
	[<000000004ebfffcd>] alloc_bulk+0x2af/0x720
	[<00000000d9c10145>] prefill_mem_cache+0x7f/0xb0
	[<00000000ff9738ff>] bpf_mem_alloc_init+0x3e2/0x610
	[<000000008b616eac>] bpf_global_ma_init+0x19/0x30
	[<00000000fc473efc>] do_one_initcall+0xd3/0x3c0
	[<00000000ec81498c>] kernel_init_freeable+0x66a/0x940
	[<00000000b119f72f>] kernel_init+0x20/0x160
	[<00000000f11ac9a7>] ret_from_fork+0x3c/0x70
	[<0000000004671da4>] ret_from_fork_asm+0x1a/0x30

That is because nr_bits will be set as zero in bpf_iter_bits_next()
after all bits have been iterated.

Fix the issue by setting kit->bit to kit->nr_bits instead of setting
kit->nr_bits to zero when the iteration completes in
bpf_iter_bits_next(). In addition, use "!nr_bits || bits >= nr_bits" to
check whether the iteration is complete and still use "nr_bits > 64" to
indicate whether bits are dynamically allocated. The "!nr_bits" check is
necessary because bpf_iter_bits_new() may fail before setting
kit->nr_bits, and this condition will stop the iteration early instead
of accessing the zeroed or freed kit->bits.

Considering the initial value of kit->bits is -1 and the type of
kit->nr_bits is unsigned int, change the type of kit->nr_bits to int.
The potential overflow problem will be handled in the following patch.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2024-50254?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-50254?

Apply the vendor's patch.

## Is CVE-2024-50254 being exploited?

There is no known exploitation of CVE-2024-50254 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-2024-50254 and fix it if it is affected.

What it is: CVE-2024-50254 is a medium-severity memory corruption vulnerability in Linux kernel, published on 9 Nov 2024. 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-2024-50254 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-2024-50254/ (Markdown: https://insights.sbomify.com/CVE-2024-50254/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-50254
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-50254
- OSV: https://osv.dev/vulnerability/CVE-2024-50254

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-50254/
Summaries are generated and may contain mistakes; the official description above is the record.