# CVE-2024-50194: arm64: probes: Fix uprobes for big-endian kernels

> Incorrect endianness handling in arm64 uprobes on big-endian kernels can cause instruction simulation errors, leading to potential crashes or incorrect execution.

- **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:** 8 Nov 2024
- **Updated:** 11 May 2026
- **Also known as:** AZL-53435, AZL-53654, BELL-CVE-2024-50194, DEBIAN-CVE-2024-50194, GHSA-8p49-gjw4-jcmp, UBUNTU-CVE-2024-50194

## What is CVE-2024-50194?

CVE-2024-50194 is a medium-severity vulnerability in Linux kernel, published on 8 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:

arm64: probes: Fix uprobes for big-endian kernels

The arm64 uprobes code is broken for big-endian kernels as it doesn't
convert the in-memory instruction encoding (which is always
little-endian) into the kernel's native endianness before analyzing and
simulating instructions. This may result in a few distinct problems:

* The kernel may may erroneously reject probing an instruction which can
  safely be probed.

* The kernel may erroneously erroneously permit stepping an
  instruction out-of-line when that instruction cannot be stepped
  out-of-line safely.

* The kernel may erroneously simulate instruction incorrectly dur to
  interpretting the byte-swapped encoding.

The endianness mismatch isn't caught by the compiler or sparse because:

* The arch_uprobe::{insn,ixol} fields are encoded as arrays of u8, so
  the compiler and sparse have no idea these contain a little-endian
  32-bit value. The core uprobes code populates these with a memcpy()
  which similarly does not handle endianness.

* While the uprobe_opcode_t type is an alias for __le32, both
  arch_uprobe_analyze_insn() and arch_uprobe_skip_sstep() cast from u8[]
  to the similarly-named probe_opcode_t, which is an alias for u32.
  Hence there is no endianness conversion warning.

Fix this by changing the arch_uprobe::{insn,ixol} fields to __le32 and
adding the appropriate __le32_to_cpu() conversions prior to consuming
the instruction encoding. The core uprobes copies these fields as opaque
ranges of bytes, and so is unaffected by this change.

At the same time, remove MAX_UINSN_BYTES and consistently use
AARCH64_INSN_SIZE for clarity.

Tested with the following:

| #include <stdio.h>
| #include <stdbool.h>
|
| #define noinline __attribute__((noinline))
|
| static noinline void *adrp_self(void)
| {
|         void *addr;
|
|         asm volatile(
|         "       adrp    %x0, adrp_self\n"
|         "       add     %x0, %x0, :lo12:adrp_self\n"
|         : "=r" (addr));
| }
|
|
| int main(int argc, char *argv)
| {
|         void *ptr = adrp_self();
|         bool equal = (ptr == adrp_self);
|
|         printf("adrp_self   => %p\n"
|                "adrp_self() => %p\n"
|                "%s\n",
|                adrp_self, ptr, equal ? "EQUAL" : "NOT EQUAL");
|
|         return 0;
| }

.... where the adrp_self() function was compiled to:

| 00000000004007e0 <adrp_self>:
|   4007e0:       90000000        adrp    x0, 400000 <__ehdr_start>
|   4007e4:       911f8000        add     x0, x0, #0x7e0
|   4007e8:       d65f03c0        ret

Before this patch, the ADRP is not recognized, and is assumed to be
steppable, resulting in corruption of the result:

| # ./adrp-self
| adrp_self   => 0x4007e0
| adrp_self() => 0x4007e0
| EQUAL
| # echo 'p /root/adrp-self:0x007e0' > /sys/kernel/tracing/uprobe_events
| # echo 1 > /sys/kernel/tracing/events/uprobes/enable
| # ./adrp-self
| adrp_self   => 0x4007e0
| adrp_self() => 0xffffffffff7e0
| NOT EQUAL

After this patch, the ADRP is correctly recognized and simulated:

| # ./adrp-self
| adrp_self   => 0x4007e0
| adrp_self() => 0x4007e0
| EQUAL
| #
| # echo 'p /root/adrp-self:0x007e0' > /sys/kernel/tracing/uprobe_events
| # echo 1 > /sys/kernel/tracing/events/uprobes/enable
| # ./adrp-self
| adrp_self   => 0x4007e0
| adrp_self() => 0x4007e0
| EQUAL

## Which versions are affected by CVE-2024-50194?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-50194?

Apply the vendor's patch.

## Is CVE-2024-50194 being exploited?

There is no known exploitation of CVE-2024-50194 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-2024-50194 and fix it if it is affected.

What it is: CVE-2024-50194 is a medium-severity vulnerability in Linux kernel, published on 8 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-2024-50194 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-2024-50194/ (Markdown: https://insights.sbomify.com/CVE-2024-50194/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-50194
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-50194
- OSV: https://osv.dev/vulnerability/CVE-2024-50194

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-50194/
Summaries are generated and may contain mistakes; the official description above is the record.