Operation on a resource after expiration or release in Linux kernel - CVE-2019-15794

Vulnerability identifier: #VU92769

CSH Severity: Low

CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2019-15794

CWE-ID: CWE-672

Exploitation vector: Local access

Exploit availability: Public exploit is available

The vulnerability allows a local privileged user to execute arbitrary code.

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.

Linux kernel
Ubuntu
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-hwe (Ubuntu package)
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-kvm (Ubuntu package)
linux-raspi2 (Ubuntu package)
linux-oracle-5.0 (Ubuntu package)
linux-oem-osp1 (Ubuntu package)
linux-gke-5.0 (Ubuntu package)
linux-aws-5.0 (Ubuntu package)

Install update from vendor's repository.

linux-gcp (Ubuntu package) - addressed in versions 5.0.0-1026.27~18.04.1, 5.0.0-1026.27
linux-oracle (Ubuntu package) - update to 5.0.0-1008.13
linux-hwe (Ubuntu package) - update to 5.0.0-37.40~18.04.1
linux (Ubuntu package) - update to 5.0.0-37.40
linux-aws (Ubuntu package) - update to 5.0.0-1022.25
linux-kvm (Ubuntu package) - update to 5.0.0-1023.25
linux-raspi2 (Ubuntu package) - update to 5.0.0-1023.24
linux-oracle-5.0 (Ubuntu package) - update to 5.0.0-1008.13~18.04.1
linux-oem-osp1 (Ubuntu package) - update to 5.0.0-1030.34
linux-gke-5.0 (Ubuntu package) - update to 5.0.0-1026.27~18.04.2
linux-aws-5.0 (Ubuntu package) - update to 5.0.0-1022.25~18.04.1

• Exploit #10052 - Ubuntu 19.10 - ubuntu-aufs-modified mmap_region() Breaks Refcounting in overlayfs/shiftfs Error Path (June 20, 2024)

• https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=270d16ae48a4dbf1c7e25e94cc3e38b4bea37635
• https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=ef81780548d20a786cc77ed4203fca146fd81ce3
• https://usn.ubuntu.com/usn/usn-4208-1
• https://usn.ubuntu.com/usn/usn-4209-1

• Operation on a resource after expiration or release in Linux kernel
• Ubuntu update for linux, linux-aws, linux-aws-5.0 and more