A use-after-free vulnerability in the Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component can be exploited to achieve local privilege escalation.
If a class with a link-sharing curve (i.e. with the HFSCFSC flag set) has a parent without a link-sharing curve, then initvf() will call vttreeinsert() on the parent, but vttreeremove() will be skipped in update_vf(). This leaves a dangling pointer that can cause a use-after-free.
We recommend upgrading past commit b3d26c5702c7d6c45456326e56d2ccf3f103e60f.
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-4623.json"
[
{
"id": "CVE-2023-4623-01491a2e",
"target": {
"file": "net/sched/sch_hfsc.c"
},
"signature_version": "v1",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git@b3d26c5702c7d6c45456326e56d2ccf3f103e60f",
"digest": {
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{
"id": "CVE-2023-4623-245dda27",
"target": {
"function": "hfsc_change_class",
"file": "net/sched/sch_hfsc.c"
},
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"source": "https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git@b3d26c5702c7d6c45456326e56d2ccf3f103e60f",
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]