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;

kernel.org https://git.kernel.org/stable/c/03c71c42809ef4b17f5d874cdb2d3bf40e847b86 [No types assigned]

kernel.org https://git.kernel.org/stable/c/1b4a8b89bf6787090b56424d269bf84ba00c3263 [No types assigned]

kernel.org https://git.kernel.org/stable/c/39bc27bd688066a63e56f7f64ad34fae03fbe3b8 [No types assigned]