{"id":"CVE-2024-35860","title":"bpf: support deferring bpf_link dealloc to after RCU grace period","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: support deferring bpf_link dealloc to after RCU grace period\n\nBPF link for some program types is passed as a \"context\" which can be\nused by those BPF programs to l…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 0dcac272540613d41c05e89679e4ddb978b612f1 < ac48dc6ac9240f73bf08d29edf65c2deca93ee5d","Linux >= 0dcac272540613d41c05e89679e4ddb978b612f1 < 876941f533e7b47fc69977fc4551c02f2d18af97","Linux >= 0dcac272540613d41c05e89679e4ddb978b612f1 < 5d8d447777564b35f67000e7838e7ccb64d525c8","Linux >= 0dcac272540613d41c05e89679e4ddb978b612f1 < 1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce","Linux 5.18"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2024-09-10T15:41:33.868687Z"},"published":"2024-05-19","updated":"2026-10-30","sourceUpdated":"2026-10-30T12:18:16.969Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2024-35860","references":[{"url":"https://git.kernel.org/stable/c/ac48dc6ac9240f73bf08d29edf65c2deca93ee5d"},{"url":"https://git.kernel.org/stable/c/876941f533e7b47fc69977fc4551c02f2d18af97"},{"url":"https://git.kernel.org/stable/c/5d8d447777564b35f67000e7838e7ccb64d525c8"},{"url":"https://git.kernel.org/stable/c/1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce"}],"tags":["cve.org"],"epss":0.00236,"epssPercentile":0.14665,"ingestedAt":"2026-11-03T12:44:28.812Z","slug":"CVE-2024-35860","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf: support deferring bpf_link dealloc to after RCU grace period\n\nBPF link for some program types is passed as a \"context\" which can be\nused by those BPF programs to look up additional information. E.g., for\nmulti-kprobes and multi-uprobes, link is used to fetch BPF cookie values.\n\nBecause of this runtime dependency, when bpf_link refcnt drops to zero\nthere could still be active BPF programs running accessing link data.\n\nThis patch adds generic support to defer bpf_link dealloc callback to\nafter RCU GP, if requested. This is done by exposing two different\ndeallocation callbacks, one synchronous and one deferred. If deferred\none is provided, bpf_link_free() will schedule dealloc_deferred()\ncallback to happen after RCU GP.\n\nBPF is using two flavors of RCU: \"classic\" non-sleepable one and RCU\ntasks trace one. The latter is used when sleepable BPF programs are\nused. bpf_link_free() accommodates that by checking underlying BPF\nprogram's sleepable flag, and goes either through normal RCU GP only for\nnon-sleepable, or through RCU tasks trace GP *and* then normal RCU GP\n(taking into account rcu_trace_implies_rcu_gp() optimization), if BPF\nprogram is sleepable.\n\nWe use this for multi-kprobe and multi-uprobe links, which dereference\nlink during program run. We also preventively switch raw_tp link to use\ndeferred dealloc callback, as upcoming changes in bpf-next tree expose\nraw_tp link data (specifically, cookie value) to BPF program at runtime\nas well.\n\n## Affected\n\n- `Linux >= 0dcac272540613d41c05e89679e4ddb978b612f1 < ac48dc6ac9240f73bf08d29edf65c2deca93ee5d`\n- `Linux >= 0dcac272540613d41c05e89679e4ddb978b612f1 < 876941f533e7b47fc69977fc4551c02f2d18af97`\n- `Linux >= 0dcac272540613d41c05e89679e4ddb978b612f1 < 5d8d447777564b35f67000e7838e7ccb64d525c8`\n- `Linux >= 0dcac272540613d41c05e89679e4ddb978b612f1 < 1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce`\n- `Linux 5.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}