SB2021060728 - Privilege escalation in Linux kernel ucma driver
Published: June 7, 2021 Updated: December 6, 2021
Security Bulletin ID
SB2021060728
Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Use-after-free (CVE-ID: CVE-2020-36385)
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a use-after-free error in drivers/infiniband/core/ucma.c, because the ctx is reached via the ctx_list in some ucma_migrate_id situations where ucma_close is called. A local user can run a specially crafted program to trigger the use-after-free error and execute arbitrary code with elevated privileges.
Remediation
Install update from vendor's website.
References
- https://syzkaller.appspot.com/bug?id=457491c4672d7b52c1007db213d93e47c711fae6
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f5449e74802c1112dea984aec8af7a33c4516af1
- https://sites.google.com/view/syzscope/kasan-use-after-free-read-in-ucma_close-2
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.10