{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-42108", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-07-29T15:50:41.176Z", "datePublished": "2024-07-30T07:46:03.517Z", "dateUpdated": "2026-08-05T11:35:40.063Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:35:40.063Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: rswitch: Avoid use-after-free in rswitch_poll()\n\nThe use-after-free is actually in rswitch_tx_free(), which is inlined in\nrswitch_poll(). Since `skb` and `gq->skbs[gq->dirty]` are in fact the\nsame pointer, the skb is first freed using dev_kfree_skb_any(), then the\nvalue in skb->len is used to update the interface statistics.\n\nLet's move around the instructions to use skb->len before the skb is\nfreed.\n\nThis bug is trivial to reproduce using KFENCE. It will trigger a splat\nevery few packets. A simple ARP request or ICMP echo request is enough." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The UAF fires on every hardware TX completion, and an unauthenticated remote host reaches it simply by sending any packet that elicits a reply (ICMP echo request, TCP SYN to a closed port, any service response) — all routable across L3, not just link-local. The fix commit itself states an ARP or ICMP echo request is sufficient to trigger it.\nAC:L - There is no race, no timing window, and no memory-layout precondition — `skb->len` is read unconditionally one statement after `dev_kfree_skb_any()` on every TX-completed skb, and the attacker sets the pace by sending packets. The commit reports a splat \"every few packets,\" so even the KFENCE-guarded-slot case is hit trivially by a sustained flood.\nPR:N - The reply packet is generated by the kernel network stack before any application-layer authentication, so no credentials, session, or account on the target are needed. Recovering the leaked word afterwards requires only a world-readable counter in `/proc/net/dev`.\nUI:N - The attacker sends the packets themselves and the TX-completion NAPI poll runs autonomously; no victim login, mount, file open, or any other action is involved.\nS:U - The use-after-free read, the leaked freelist word, and the resulting fault all stay inside the kernel's own memory and the rswitch driver's security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Because `skbuff_head_cache` has no ctor/RCU/poison flags, SLUB places the freelist pointer at ~offset 112 — precisely where `skb->len` sits — so the freed-memory read pulls the low 32 bits of a kernel heap pointer and adds it into `stats.tx_bytes`, which `rswitch_get_stats()` exports verbatim to `/proc/net/dev` and sysfs. Differencing the counter around a single TX completion recovers that word exactly and repeatably, giving a reliable kernel heap-address/KASLR disclosure; per kernel scoring guidance a use-after-free is High regardless.\nI:H - This is a use-after-free on an object in the general-purpose `skbuff_head_cache`, which per kernel scoring guidance is rated High since freed-object accesses in that cache are the standard primitive for heap grooming and control-flow corruption. Concretely, kernel-maintained interface accounting is corrupted with freed slab contents, poisoning the statistics that monitoring and traffic-accounting decisions rely on.\nA:H - On the many kernels shipping `CONFIG_KFENCE=y` (Android GKI, Fedora, RHEL, Ubuntu, hardened automotive builds) the freed object's page is unmapped, so the `skb->len` read page-faults into `kfence_report_error()`, which calls `check_panic_on_warn(\"KFENCE\")` — an immediate kernel panic on the fail-fast configurations typical for an in-vehicle R-Car S4 gateway. A remote attacker can drive this indefinitely with a ping flood, and any use-after-free is rated High for availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/renesas/rswitch.c" ], "versions": [ { "version": "0aeec4bb6a9fc963932bf3c929bdf27d835d44e9", "lessThan": "4a41bb9f2b402469d425a1c13359d3b3ea4e6403", "status": "affected", "versionType": "git" }, { "version": "271e015b91535dd87fd0f5df0cc3b906c2eddef9", "lessThan": "92cbbe7759193e3418f38d0d73f8fe125312c58b", "status": "affected", "versionType": "git" }, { "version": "271e015b91535dd87fd0f5df0cc3b906c2eddef9", "lessThan": "9a0c28efeec6383ef22e97437616b920e7320b67", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/renesas/rswitch.c" ], "versions": [ { "version": "6.8", "status": "affected" }, { "version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.9", "lessThanOrEqual": "6.9.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.9.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.10" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/4a41bb9f2b402469d425a1c13359d3b3ea4e6403" }, { "url": "https://git.kernel.org/stable/c/92cbbe7759193e3418f38d0d73f8fe125312c58b" }, { "url": "https://git.kernel.org/stable/c/9a0c28efeec6383ef22e97437616b920e7320b67" } ], "title": "net: rswitch: Avoid use-after-free in rswitch_poll()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-02T04:54:32.138Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/92cbbe7759193e3418f38d0d73f8fe125312c58b", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/9a0c28efeec6383ef22e97437616b920e7320b67", "tags": [ "x_transferred" ] } ] }, { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2024-42108", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-09-10T16:17:39.409257Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-09-11T17:33:07.014Z" } } ] } }