CVE-2019-15794

Reference counting error in overlayfs/shiftfs error path when used in conjuction with aufs

Published Apr 23, 2020 CVSS 3.1 · 7.1 High EPSS 1.2% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2019-6717 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.
Ubuntu USN Ubuntu USN USN-4208-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-4209-1 Linux kernel vulnerabilities
History
Type Values Removed Values Added
First Time appeared Redhat
Redhat enterprise Linux
CPEs cpe:/o:redhat:enterprise_linux:8
Vendors & Products Redhat
Redhat enterprise Linux
Weaknesses

Sources

Status
PUBLISHED
Assigner
canonical
Published
Updated
Sep 16, 2024, 7:52 PM
Reserved
Aug 29, 2019, 12:00 AM
Status
Modified
Published
Apr 24, 2020, 12:15 AM
Modified
Jun 17, 2026, 2:21 AM
Severity
Moderate
Public date
Nov 12, 2019, 12:00 AM