cbcvebase.
CVE-2024-35860
published 2024-05-19

CVE-2024-35860: 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…

PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.22%
13.3th percentile
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.

Affected

12 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.8.9-1 (forky)linux 6.8.9-1 (forky)
linuxlinux
linuxlinux>= 0dcac272540613d41c05e89679e4ddb978b612f1 < 876941f533e7b47fc69977fc4551c02f2d18af97876941f533e7b47fc69977fc4551c02f2d18af97
linuxlinux>= 0dcac272540613d41c05e89679e4ddb978b612f1 < 5d8d447777564b35f67000e7838e7ccb64d525c85d8d447777564b35f67000e7838e7ccb64d525c8
linuxlinux>= 0dcac272540613d41c05e89679e4ddb978b612f1 < 1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.8.9-16.8.9-1
linuxlinux_kernel>= 0 < 6.8.9-16.8.9-1
linuxlinux_kernel>= 0 < 6.8.0-38.386.8.0-38.38
linuxlinux_kernel>= 5.18 < 6.6.266.6.26
linuxlinux_kernel>= 6.7 < 6.8.56.8.5

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv6.8MEDIUM
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
vendor_ubuntu4.6MEDIUM
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