Bug 1951595 (CVE-2021-29155)
| Summary: | CVE-2021-29155 kernel: protection for sequences of pointer arithmetic operations against speculatively out-of-bounds loads can be bypassed to leak content of kernel memory | ||
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| Product: | [Other] Security Response | Reporter: | Guilherme de Almeida Suckevicz <gsuckevi> |
| Component: | vulnerability | Assignee: | Red Hat Product Security <security-response-team> |
| Status: | CLOSED ERRATA | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | unspecified | CC: | acaringi, adscvr, airlied, alciregi, bhu, bmasney, brdeoliv, bskeggs, chwhite, crwood, dhoward, dvlasenk, fhrbata, fpacheco, hdegoede, hkrzesin, jarodwilson, jeremy, jforbes, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, nmurray, ptalbert, qzhao, rkeshri, rvrbovsk, steved, walters, wcosta, williams |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Kernel 5.12 | Doc Type: | If docs needed, set a value |
| Doc Text: |
A vulnerability was discovered in retrieve_ptr_limit in kernel/bpf/verifier.c in the Linux kernel mechanism to mitigate speculatively out-of-bounds loads (Spectre mitigation). In this flaw a local, special user privileged (CAP_SYS_ADMIN) BPF program running on affected systems may bypass the protection, and execute speculatively out-of-bounds loads from the kernel memory. This can be abused to extract contents of kernel memory via side-channel.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | 2021-11-09 20:24:28 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | 1951597, 1960942, 1960943, 1960944, 1960945, 1961563, 1961564, 1961565, 1961566 | ||
| Bug Blocks: | 1951598 | ||
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Description
Guilherme de Almeida Suckevicz
2021-04-20 14:29:12 UTC
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 1951597] External References: https://www.openwall.com/lists/oss-security/2021/04/18/4 Mitigation: The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl. This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space. For the Red Hat Enterprise Linux 7 the eBPF for unprivileged users is always disabled. For the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command: # cat /proc/sys/kernel/unprivileged_bpf_disabled The setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw. A kernel update will be required to mitigate the flaw for the root or users with CAP_SYS_ADMIN capabilities. This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2021:4140 https://access.redhat.com/errata/RHSA-2021:4140 This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2021:4356 https://access.redhat.com/errata/RHSA-2021:4356 This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2021-29155 |