Description
The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and therefore, arbitrary code execution. This issue was fixed via commit 049c4e13714e ("bpf: Fix alu32 const subreg bound tracking on bitwise operations") (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. The AND/OR issues were introduced by commit 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking") (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 ("bpf:Fix a verifier failure with xor") ( 5.10-rc1).
CVSS breakdown
CVSS 3.1
Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High
Affected products
- Linux / Linux kerneltrunk – v5.13-rc4
- Linux / Linux kernellinux-5.12.y – v5.12.4
- Linux / Linux kernellinux-5.11.y – v5.11.21
- Linux / Linux kernellinux-5.10.y – v5.10.37
- Linux / Linux kernelv5.7-rc1 – 5.7*
References
- VENDOR_ADVISORYhttps://ubuntu.com/security/notices/USN-4950-1
- VENDOR_ADVISORYhttps://ubuntu.com/security/notices/USN-4949-1
- MAILING_LISThttps://www.openwall.com/lists/oss-security/2021/05/11/11
- MISChttps://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e
- VENDOR_ADVISORYhttps://www.zerodayinitiative.com/advisories/ZDI-21-606/
- MISChttps://security.netapp.com/advisory/ntap-20210716-0004/
- EXPLOIThttp://packetstormsecurity.com/files/164015/Linux-eBPF-ALU32-32-bit-Invalid-Bounds-Tracking-Local-Privilege-Escalation.html