vulnerability

Ubuntu: (Multiple Advisories) (CVE-2024-35860): Linux kernel vulnerabilities

Severity
5
CVSS
(AV:L/AC:L/Au:S/C:N/I:N/A:C)
Published
05/19/2024
Added
07/12/2024
Modified
02/20/2025

Description

In the Linux kernel, the following vulnerability has been resolved:

bpf: support deferring bpf_link dealloc to after RCU grace period

BPF link for some program types is passed as a "context" which can be
used by those BPF programs to look up additional information. E.g., for
multi-kprobes and multi-uprobes, link is used to fetch BPF cookie values.

Because of this runtime dependency, when bpf_link refcnt drops to zero
there could still be active BPF programs running accessing link data.

This patch adds generic support to defer bpf_link dealloc callback to
after RCU GP, if requested. This is done by exposing two different
deallocation callbacks, one synchronous and one deferred. If deferred
one is provided, bpf_link_free() will schedule dealloc_deferred()
callback to happen after RCU GP.

BPF is using two flavors of RCU: "classic" non-sleepable one and RCU
tasks trace one. The latter is used when sleepable BPF programs are
used. bpf_link_free() accommodates that by checking underlying BPF
program's sleepable flag, and goes either through normal RCU GP only for
non-sleepable, or through RCU tasks trace GP *and* then normal RCU GP
(taking into account rcu_trace_implies_rcu_gp() optimization), if BPF
program is sleepable.

We use this for multi-kprobe and multi-uprobe links, which dereference
link during program run. We also preventively switch raw_tp link to use
deferred dealloc callback, as upcoming changes in bpf-next tree expose
raw_tp link data (specifically, cookie value) to BPF program at runtime
as well.

Solution(s)

ubuntu-upgrade-linux-image-6-8-0-1006-gkeubuntu-upgrade-linux-image-6-8-0-1007-intelubuntu-upgrade-linux-image-6-8-0-1007-raspiubuntu-upgrade-linux-image-6-8-0-1008-ibmubuntu-upgrade-linux-image-6-8-0-1008-oemubuntu-upgrade-linux-image-6-8-0-1008-oracleubuntu-upgrade-linux-image-6-8-0-1008-oracle-64kubuntu-upgrade-linux-image-6-8-0-1009-nvidiaubuntu-upgrade-linux-image-6-8-0-1009-nvidia-64kubuntu-upgrade-linux-image-6-8-0-1010-azureubuntu-upgrade-linux-image-6-8-0-1010-azure-fdeubuntu-upgrade-linux-image-6-8-0-1010-gcpubuntu-upgrade-linux-image-6-8-0-1011-awsubuntu-upgrade-linux-image-6-8-0-38-genericubuntu-upgrade-linux-image-6-8-0-38-generic-64kubuntu-upgrade-linux-image-6-8-0-38-lowlatencyubuntu-upgrade-linux-image-6-8-0-38-lowlatency-64kubuntu-upgrade-linux-image-awsubuntu-upgrade-linux-image-azureubuntu-upgrade-linux-image-azure-fdeubuntu-upgrade-linux-image-gcpubuntu-upgrade-linux-image-genericubuntu-upgrade-linux-image-generic-64kubuntu-upgrade-linux-image-generic-64k-hwe-24-04ubuntu-upgrade-linux-image-generic-hwe-24-04ubuntu-upgrade-linux-image-generic-lpaeubuntu-upgrade-linux-image-gkeubuntu-upgrade-linux-image-ibmubuntu-upgrade-linux-image-ibm-classicubuntu-upgrade-linux-image-ibm-lts-24-04ubuntu-upgrade-linux-image-intelubuntu-upgrade-linux-image-kvmubuntu-upgrade-linux-image-lowlatencyubuntu-upgrade-linux-image-lowlatency-64kubuntu-upgrade-linux-image-nvidiaubuntu-upgrade-linux-image-nvidia-64kubuntu-upgrade-linux-image-oem-24-04ubuntu-upgrade-linux-image-oem-24-04aubuntu-upgrade-linux-image-oracleubuntu-upgrade-linux-image-oracle-64kubuntu-upgrade-linux-image-raspiubuntu-upgrade-linux-image-virtualubuntu-upgrade-linux-image-virtual-hwe-24-04
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