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.
History

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cve-icon MITRE

Status: PUBLISHED

Assigner: canonical

Published: 2020-04-23T23:55:25.039982Z

Updated: 2024-09-16T19:52:18.313Z

Reserved: 2019-08-29T00:00:00

Link: CVE-2019-15794

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2020-04-24T00:15:11.933

Modified: 2020-05-26T15:18:52.653

Link: CVE-2019-15794

cve-icon Redhat

Severity : Moderate

Publid Date: 2019-11-12T00:00:00Z

Links: CVE-2019-15794 - Bugzilla