Overlayfs in the Linux kernel and shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, both replace vma->vm_file in their mmap handlers. On error the original value is not restored, and the reference is put for the file to which vm_file points. On upstream kernels this is not an issue, as no callers dereference vm_file following after call_mmap() returns an error. However, the aufs patchs change mmap_region() to replace the fput() using a local variable with vma_fput(), which will fput() vm_file, leading to a refcount underflow.
The product uses, accesses, or otherwise operates on a resource after that resource has been expired, released, or revoked.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Linux_kernel | Linux | 5.0 (including) | 5.0 (including) |
| Linux_kernel | Linux | 5.3 (including) | 5.3 (including) |