CVE-2024-35860 Affecting kernel-core package, versions *
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Test your applications- Snyk ID SNYK-RHEL9-KERNELCORE-6935094
- published 21 May 2024
- disclosed 19 May 2024
Introduced: 19 May 2024
CVE-2024-35860 Open this link in a new tabHow to fix?
There is no fixed version for RHEL:9 kernel-core.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-core package and not the kernel-core package as distributed by RHEL.
See How to fix? for RHEL:9 relevant fixed versions and status.
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.