CVE-2019-15794

Summary

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.

Affected Software

VendorProductVersion RangeStatus
UbuntuLinux kernel5.3 kernel < 5.3.0-24.26affected
UbuntuLinux kernel5.0 kernel < 5.0.0-37.40affected

Weaknesses

  • CWE-672: CWE-672 Operation on a Resource after Expiration or Release

ADP Enrichment

CVE Program Container

Additional References

References