{"id":"CVE-2024-41010","state":"PUBLISHED","title":"bpf: Fix too early release of tcx_entry","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix too early release of tcx_entry\n\nPedro Pinto and later independently also Hyunwoo Kim and Wongi Lee reported\nan issue that the tcx_entry can be released too early leading to a use\nafter free (UAF) when an active old-style ingress or clsact qdisc with a\nshared tc block is later replaced by another ingress or clsact instance.\n\nEssentially, the sequence to trigger the UAF (one example) can be as follows:\n\n  1. A network namespace is created\n  2. An ingress qdisc is created. This allocates a tcx_entry, and\n     &tcx_entry->miniq is stored in the qdisc's miniqp->p_miniq. At the\n     same time, a tcf block with index 1 is created.\n  3. chain0 is attached to the tcf block. chain0 must be connected to\n     the block linked to the ingress qdisc to later reach the function\n     tcf_chain0_head_change_cb_del() which triggers the UAF.\n  4. Create and graft a clsact qdisc. This causes the ingress qdisc\n     created in step 1 to be removed, thus freeing the previously linked\n     tcx_entry:\n\n     rtnetlink_rcv_msg()\n       => tc_modify_qdisc()\n         => qdisc_create()\n           => clsact_init() [a]\n         => qdisc_graft()\n           => qdisc_destroy()\n             => __qdisc_destroy()\n               => ingress_destroy() [b]\n                 => tcx_entry_free()\n                   => kfree_rcu() // tcx_entry freed\n\n  5. Finally, the network namespace is closed. This registers the\n     cleanup_net worker, and during the process of releasing the\n     remaining clsact qdisc, it accesses the tcx_entry that was\n     already freed in step 4, causing the UAF to occur:\n\n     cleanup_net()\n       => ops_exit_list()\n         => default_device_exit_batch()\n           => unregister_netdevice_many()\n             => unregister_netdevice_many_notify()\n               => dev_shutdown()\n                 => qdisc_put()\n                   => clsact_destroy() [c]\n                     => tcf_block_put_ext()\n                       => tcf_chain0_head_change_cb_del()\n                         => tcf_chain_head_change_item()\n                           => clsact_chain_head_change()\n                             => mini_qdisc_pair_swap() // UAF\n\nThere are also other variants, the gist is to add an ingress (or clsact)\nqdisc with a specific shared block, then to replace that qdisc, waiting\nfor the tcx_entry kfree_rcu() to be executed and subsequently accessing\nthe current active qdisc's miniq one way or another.\n\nThe correct fix is to turn the miniq_active boolean into a counter. What\ncan be observed, at step 2 above, the counter transitions from 0->1, at\nstep [a] from 1->2 (in order for the miniq object to remain active during\nthe replacement), then in [b] from 2->1 and finally [c] 1->0 with the\neventual release. The reference counter in general ranges from [0,2] and\nit does not need to be atomic since all access to the counter is protected\nby the rtnl mutex. With this in place, there is no longer a UAF happening\nand the tcx_entry is freed at the correct time.","publishedAt":"2024-07-17T06:10:12.051Z","updatedAt":"2026-08-05T11:34:36.731Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e420bed025071a623d2720a92bc2245c84757ecb","status":"affected","lessThan":"230bb13650b0f186f540500fd5f5f7096a822a2a","versionType":"git"},{"version":"e420bed025071a623d2720a92bc2245c84757ecb","status":"affected","lessThan":"f61ecf1bd5b562ebfd7d430ccb31619857e80857","versionType":"git"},{"version":"e420bed025071a623d2720a92bc2245c84757ecb","status":"affected","lessThan":"1cb6f0bae50441f4b4b32a28315853b279c7404e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/tcx.h","net/sched/sch_ingress.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.6","versionType":"semver"},{"version":"6.6.41","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.9.10","status":"unaffected","lessThanOrEqual":"6.9.*","versionType":"semver"},{"version":"6.10","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/tcx.h","net/sched/sch_ingress.c"]}],"references":["https://git.kernel.org/stable/c/230bb13650b0f186f540500fd5f5f7096a822a2a","https://git.kernel.org/stable/c/f61ecf1bd5b562ebfd7d430ccb31619857e80857","https://git.kernel.org/stable/c/1cb6f0bae50441f4b4b32a28315853b279c7404e"],"weaknesses":[],"ingestedAt":"2026-10-29T20:07:39.287Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2024/41xxx/CVE-2024-41010.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-41010","state":"PUBLISHED","datePublished":"2024-07-17T06:10:12.051Z","dateUpdated":"2026-08-05T11:34:36.731Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-07-12T12:17:45.610Z"},"containers":{"cna":{"title":"bpf: Fix too early release of tcx_entry","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix too early release of tcx_entry\n\nPedro Pinto and later independently also Hyunwoo Kim and Wongi Lee reported\nan issue that the tcx_entry can be released too early leading to a use\nafter free (UAF) when an active old-style ingress or clsact qdisc with a\nshared tc block is later replaced by another ingress or clsact instance.\n\nEssentially, the sequence to trigger the UAF (one example) can be as follows:\n\n  1. A network namespace is created\n  2. An ingress qdisc is created. This allocates a tcx_entry, and\n     &tcx_entry->miniq is stored in the qdisc's miniqp->p_miniq. At the\n     same time, a tcf block with index 1 is created.\n  3. chain0 is attached to the tcf block. chain0 must be connected to\n     the block linked to the ingress qdisc to later reach the function\n     tcf_chain0_head_change_cb_del() which triggers the UAF.\n  4. Create and graft a clsact qdisc. This causes the ingress qdisc\n     created in step 1 to be removed, thus freeing the previously linked\n     tcx_entry:\n\n     rtnetlink_rcv_msg()\n       => tc_modify_qdisc()\n         => qdisc_create()\n           => clsact_init() [a]\n         => qdisc_graft()\n           => qdisc_destroy()\n             => __qdisc_destroy()\n               => ingress_destroy() [b]\n                 => tcx_entry_free()\n                   => kfree_rcu() // tcx_entry freed\n\n  5. Finally, the network namespace is closed. This registers the\n     cleanup_net worker, and during the process of releasing the\n     remaining clsact qdisc, it accesses the tcx_entry that was\n     already freed in step 4, causing the UAF to occur:\n\n     cleanup_net()\n       => ops_exit_list()\n         => default_device_exit_batch()\n           => unregister_netdevice_many()\n             => unregister_netdevice_many_notify()\n               => dev_shutdown()\n                 => qdisc_put()\n                   => clsact_destroy() [c]\n                     => tcf_block_put_ext()\n                       => tcf_chain0_head_change_cb_del()\n                         => tcf_chain_head_change_item()\n                           => clsact_chain_head_change()\n                             => mini_qdisc_pair_swap() // UAF\n\nThere are also other variants, the gist is to add an ingress (or clsact)\nqdisc with a specific shared block, then to replace that qdisc, waiting\nfor the tcx_entry kfree_rcu() to be executed and subsequently accessing\nthe current active qdisc's miniq one way or another.\n\nThe correct fix is to turn the miniq_active boolean into a counter. What\ncan be observed, at step 2 above, the counter transitions from 0->1, at\nstep [a] from 1->2 (in order for the miniq object to remain active during\nthe replacement), then in [b] from 2->1 and finally [c] 1->0 with the\neventual release. The reference counter in general ranges from [0,2] and\nit does not need to be atomic since all access to the counter is protected\nby the rtnl mutex. With this in place, there is no longer a UAF happening\nand the tcx_entry is freed at the correct time."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e420bed025071a623d2720a92bc2245c84757ecb","status":"affected","lessThan":"230bb13650b0f186f540500fd5f5f7096a822a2a","versionType":"git"},{"version":"e420bed025071a623d2720a92bc2245c84757ecb","status":"affected","lessThan":"f61ecf1bd5b562ebfd7d430ccb31619857e80857","versionType":"git"},{"version":"e420bed025071a623d2720a92bc2245c84757ecb","status":"affected","lessThan":"1cb6f0bae50441f4b4b32a28315853b279c7404e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/tcx.h","net/sched/sch_ingress.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.6","versionType":"semver"},{"version":"6.6.41","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.9.10","status":"unaffected","lessThanOrEqual":"6.9.*","versionType":"semver"},{"version":"6.10","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/tcx.h","net/sched/sch_ingress.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/230bb13650b0f186f540500fd5f5f7096a822a2a"},{"url":"https://git.kernel.org/stable/c/f61ecf1bd5b562ebfd7d430ccb31619857e80857"},{"url":"https://git.kernel.org/stable/c/1cb6f0bae50441f4b4b32a28315853b279c7404e"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerability is reached through rtnetlink `RTM_NEWQDISC`/`RTM_NEWTFILTER` messages (`tc_modify_qdisc()` → `ingress_init`/`clsact_init`/`*_destroy`) and network-namespace teardown, all of which require local access via a netlink socket and syscalls. No remote packet can drive the qdisc configuration path.\nAC:L - The attacker deterministically controls every step — create netns, create ingress qdisc with a shared block, attach chain0, graft a clsact qdisc to free the tcx_entry, then close the netns — with all mutations serialized under the rtnl mutex, so there is no race to win, only an RCU grace period to wait out. Heap grooming of the kmalloc-2048 slot is entirely under attacker control.\nPR:L - `rtnetlink_rcv_msg()` gates qdisc creation on `netlink_net_capable(skb, CAP_NET_ADMIN)` evaluated against the netns owner's user namespace, so an unprivileged local user obtains it with `unshare -Urn` — the published trigger sequence itself begins by creating a network namespace. No real root or init-namespace privilege is needed.\nUI:N - The entire sequence is performed by the attacker's own process; the final UAF fires from the `cleanup_net` worker triggered by the attacker closing its own network namespace. No victim action of any kind is involved.\nS:U - The corruption occurs in kernel heap memory and the impact stays within the same kernel security authority (local privilege escalation). No hypervisor, IOMMU, or other security-authority boundary is crossed.\nC:H - This is a use-after-free with an attacker-timed read of the freed `tcx_entry->miniq` slot, and the reclaimed ~1.6 KB kmalloc-2048 object can be sprayed with attacker-chosen structures, giving a path to disclose kernel heap pointers and read arbitrary kernel memory via a corrupted `mini_Qdisc`/`filter_list` chain.\nI:H - `mini_qdisc_pair_swap()` writes a kernel pointer (or NULL) into offset 0 of the freed object, corrupting whatever object was reallocated there, and the write can be repeated on demand by adding/removing filters on the shared block. Combined with the RX path's indirect call through `miniq->filter_list` in `tcf_classify()`, this yields a control-flow hijack primitive suitable for full privilege escalation.\nA:H - Even without successful exploitation, the use-after-free write into freed slab memory reliably corrupts unrelated kernel objects and panics the machine (KASAN-detected UAF, oops in `mini_qdisc_pair_swap`/`cleanup_net`). It can be triggered repeatedly by any unprivileged local user."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:34:36.731Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.6.41"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.9.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.10"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/230bb13650b0f186f540500fd5f5f7096a822a2a","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/f61ecf1bd5b562ebfd7d430ccb31619857e80857","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/1cb6f0bae50441f4b4b32a28315853b279c7404e","tags":["x_transferred"]}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2024-08-02T04:39:55.990Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2024-41010","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-09-10T16:25:09.492833Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-09-11T17:34:06.652Z"}}]}}}