Bug 1959556 (CVE-2021-3490) - CVE-2021-3490 kernel: Linux kernel eBPF bitwise ops ALU32 bounds tracking
Summary: CVE-2021-3490 kernel: Linux kernel eBPF bitwise ops ALU32 bounds tracking
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2021-3490
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1963864 1959557 1963733 1963734 1963735
Blocks: 1959558
TreeView+ depends on / blocked
 
Reported: 2021-05-11 18:59 UTC by Pedro Sampaio
Modified: 2022-08-03 09:46 UTC (History)
44 users (show)

Fixed In Version: Kernel 5.13 rc4
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the Linux kernels eBPF verification code. It was discovered that eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) did not update the 32-bit bounds. By default accessing the eBPF verifier is only accessible to privileged users with CAP_SYS_ADMIN. A local user with the ability to insert eBPF instructions could use this flaw to crash the system or possibly escalate their privileges on the system.
Clone Of:
Environment:
Last Closed: 2021-11-10 16:29:39 UTC
Embargoed:

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Description Pedro Sampaio 2021-05-11 18:59:30 UTC 
A flaw was found in the Linux kernels eBPF verification code. It was discovered that eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) did not update the 32-bit bounds.  By default accessing the eBPF verifier is only accessible to privileged users with CAP_SYS_ADMIN. A local user with the ability to insert eBPF instructions could use this flaw to crash the system or possibly escalate their privileges on the system.

References:

https://www.openwall.com/lists/oss-security/2021/05/11/11
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e
Comment 1 Pedro Sampaio 2021-05-11 19:00:10 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1959557]
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