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OpenAdvisories
High · 7.1 Public exploit CVE-2019-15794 EUVD-2019-6717GHSA-33f2-r445-jvq6

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

Published Apr 23, 2020 · Updated Sep 16, 2024 · Assigned by canonical

Vendor: Ubuntu Product: Linux kernel Package: linux Package: linux Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.15 Package: linux-aws-6.14 Package: linux-aws-6.17 Package: linux-aws-6.8 Package: linux-aws-7.0 Package: linux-aws-fips Package: linux-azure Package: linux-azure-5.15 Package: linux-azure-5.3 Package: linux-azure-6.11 Package: linux-azure-6.14 Package: linux-azure-6.17 Package: linux-azure-6.8 Package: linux-azure-7.0 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.15 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.17 Package: linux-azure-fde-6.8 Package: linux-azure-fde-7.0 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-azure-nvidia-6.14 Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-5.15 Package: linux-gcp-5.3 Package: linux-gcp-6.11 Package: linux-gcp-6.14 Package: linux-gcp-6.17 Package: linux-gcp-6.8 Package: linux-gcp-7.0 Package: linux-gcp-edge Package: linux-gcp-fips Package: linux-gke Package: linux-gke-5.0 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-hwe Package: linux-hwe-5.15 Package: linux-hwe-6.11 Package: linux-hwe-6.14 Package: linux-hwe-6.17 Package: linux-hwe-6.8 Package: linux-hwe-7.0 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-5.15 Package: linux-ibm-6.8 Package: linux-intel Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-intel-iotg-5.15 Package: linux-kvm Package: linux-lowlatency Package: linux-lowlatency-hwe-5.15 Package: linux-lowlatency-hwe-6.11 Package: linux-lowlatency-hwe-6.8 Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 Package: linux-nvidia-6.8 Package: linux-nvidia-7.0 Package: linux-nvidia-bos Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-nvidia-tegra-5.15 Package: linux-nvidia-tegra-igx Package: linux-oem-6.11 Package: linux-oem-6.14 Package: linux-oem-6.17 Package: linux-oem-6.8 Package: linux-oem-7.0 Package: linux-oem-osp1 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.15 Package: linux-oracle-6.14 Package: linux-oracle-6.17 Package: linux-oracle-6.8 Package: linux-oracle-7.0 Package: linux-raspi Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.14 Package: linux-realtime-6.17 Package: linux-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.15 Package: linux-riscv-6.14 Package: linux-riscv-6.17 Package: linux-riscv-6.8 Package: linux-riscv-7.0 Package: linux-vmware Package: linux-xilinx Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

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.

Affected products

VendorProductAffectedFixed
Ubuntu Linux kernel 5.3 kernel – < 5.3.0-24.26, 5.0 kernel – < 5.0.0-37.40 5.3.0-24.26

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Debian

Security tracker ↗
ReleasePackageFixed inAdvisory
Debian 14 linux 5.16.7-1 —
Debian 13 linux 5.16.7-1 —
Debian 12 linux 5.16.7-1 —

Ubuntu

Security tracker ↗
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield No fix yet —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield No fix yet —
Ubuntu 26.10 linux +8 No fix yet —
Ubuntu 26.04 LTS linux +14 No fix yet —
Ubuntu 25.10 linux +8 No fix yet —
Show 11 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 24.04 LTS linux +53 No fix yet —
Ubuntu 22.04 LTS linux +29 No fix yet —
Ubuntu 20.04 LTS linux-gke +5 No fix yet —
Ubuntu 18.04 LTS linux-aws-5.0 5.0.0-1022.25~18.04.1 USN-4209-1
Ubuntu 18.04 LTS linux-azure 5.0.0-1027.29~18.04.1 —
Ubuntu 18.04 LTS linux-azure-5.3 5.3.0-1008.9~18.04.1 —
Ubuntu 18.04 LTS linux-gcp 5.0.0-1026.27~18.04.1 USN-4209-1
Ubuntu 18.04 LTS linux-gcp-5.3 5.3.0-1009.10~18.04.1 USN-4208-1
Ubuntu 18.04 LTS linux-gcp-edge +2 No fix yet —
Ubuntu 18.04 LTS linux-gke-5.0 5.0.0-1026.27~18.04.2 USN-4209-1
Ubuntu 18.04 LTS linux-hwe 5.0.0-37.40~18.04.1 USN-4209-1
Ubuntu 18.04 LTS linux-oem-osp1 5.0.0-1030.34 USN-4209-1
Ubuntu 18.04 LTS linux-oracle-5.0 5.0.0-1008.13~18.04.1 USN-4209-1
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-realtime +3 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-realtime +2 No fix yet —
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-preview 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 20.04 LTS linux-aws-5.15 +10 No fix yet —

Red Hat

Security tracker ↗
ReleasePackageFixed inAdvisory
RHEL 8 perf +26 4.18.0-348.el8 RHSA-2021:4356

Public exploits

Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.

Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.

Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.

Advisories 3

References