CVE-2021-47402 (GCVE-0-2021-47402)
Vulnerability from cvelistv5 – Published: 2024-05-21 15:03 – Updated: 2026-08-05 08:47
VLAI
EPSS
VEX
Title
net: sched: flower: protect fl_walk() with rcu
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: sched: flower: protect fl_walk() with rcu
Patch that refactored fl_walk() to use idr_for_each_entry_continue_ul()
also removed rcu protection of individual filters which causes following
use-after-free when filter is deleted concurrently. Fix fl_walk() to obtain
rcu read lock while iterating and taking the filter reference and temporary
release the lock while calling arg->fn() callback that can sleep.
KASAN trace:
[ 352.773640] ==================================================================
[ 352.775041] BUG: KASAN: use-after-free in fl_walk+0x159/0x240 [cls_flower]
[ 352.776304] Read of size 4 at addr ffff8881c8251480 by task tc/2987
[ 352.777862] CPU: 3 PID: 2987 Comm: tc Not tainted 5.15.0-rc2+ #2
[ 352.778980] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 352.781022] Call Trace:
[ 352.781573] dump_stack_lvl+0x46/0x5a
[ 352.782332] print_address_description.constprop.0+0x1f/0x140
[ 352.783400] ? fl_walk+0x159/0x240 [cls_flower]
[ 352.784292] ? fl_walk+0x159/0x240 [cls_flower]
[ 352.785138] kasan_report.cold+0x83/0xdf
[ 352.785851] ? fl_walk+0x159/0x240 [cls_flower]
[ 352.786587] kasan_check_range+0x145/0x1a0
[ 352.787337] fl_walk+0x159/0x240 [cls_flower]
[ 352.788163] ? fl_put+0x10/0x10 [cls_flower]
[ 352.789007] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220
[ 352.790102] tcf_chain_dump+0x231/0x450
[ 352.790878] ? tcf_chain_tp_delete_empty+0x170/0x170
[ 352.791833] ? __might_sleep+0x2e/0xc0
[ 352.792594] ? tfilter_notify+0x170/0x170
[ 352.793400] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220
[ 352.794477] tc_dump_tfilter+0x385/0x4b0
[ 352.795262] ? tc_new_tfilter+0x1180/0x1180
[ 352.796103] ? __mod_node_page_state+0x1f/0xc0
[ 352.796974] ? __build_skb_around+0x10e/0x130
[ 352.797826] netlink_dump+0x2c0/0x560
[ 352.798563] ? netlink_getsockopt+0x430/0x430
[ 352.799433] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220
[ 352.800542] __netlink_dump_start+0x356/0x440
[ 352.801397] rtnetlink_rcv_msg+0x3ff/0x550
[ 352.802190] ? tc_new_tfilter+0x1180/0x1180
[ 352.802872] ? rtnl_calcit.isra.0+0x1f0/0x1f0
[ 352.803668] ? tc_new_tfilter+0x1180/0x1180
[ 352.804344] ? _copy_from_iter_nocache+0x800/0x800
[ 352.805202] ? kasan_set_track+0x1c/0x30
[ 352.805900] netlink_rcv_skb+0xc6/0x1f0
[ 352.806587] ? rht_deferred_worker+0x6b0/0x6b0
[ 352.807455] ? rtnl_calcit.isra.0+0x1f0/0x1f0
[ 352.808324] ? netlink_ack+0x4d0/0x4d0
[ 352.809086] ? netlink_deliver_tap+0x62/0x3d0
[ 352.809951] netlink_unicast+0x353/0x480
[ 352.810744] ? netlink_attachskb+0x430/0x430
[ 352.811586] ? __alloc_skb+0xd7/0x200
[ 352.812349] netlink_sendmsg+0x396/0x680
[ 352.813132] ? netlink_unicast+0x480/0x480
[ 352.813952] ? __import_iovec+0x192/0x210
[ 352.814759] ? netlink_unicast+0x480/0x480
[ 352.815580] sock_sendmsg+0x6c/0x80
[ 352.816299] ____sys_sendmsg+0x3a5/0x3c0
[ 352.817096] ? kernel_sendmsg+0x30/0x30
[ 352.817873] ? __ia32_sys_recvmmsg+0x150/0x150
[ 352.818753] ___sys_sendmsg+0xd8/0x140
[ 352.819518] ? sendmsg_copy_msghdr+0x110/0x110
[ 352.820402] ? ___sys_recvmsg+0xf4/0x1a0
[ 352.821110] ? __copy_msghdr_from_user+0x260/0x260
[ 352.821934] ? _raw_spin_lock+0x81/0xd0
[ 352.822680] ? __handle_mm_fault+0xef3/0x1b20
[ 352.823549] ? rb_insert_color+0x2a/0x270
[ 352.824373] ? copy_page_range+0x16b0/0x16b0
[ 352.825209] ? perf_event_update_userpage+0x2d0/0x2d0
[ 352.826190] ? __fget_light+0xd9/0xf0
[ 352.826941] __sys_sendmsg+0xb3/0x130
[ 352.827613] ? __sys_sendmsg_sock+0x20/0x20
[ 352.828377] ? do_user_addr_fault+0x2c5/0x8a0
[ 352.829184] ? fpregs_assert_state_consistent+0x52/0x60
[ 352.830001] ? exit_to_user_mode_prepare+0x32/0x160
[ 352.830845] do_syscall_64+0x35/0x80
[ 352.831445] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 352.832331] RIP: 0033:0x7f7bee973c17
[
---truncated---
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-09-10 15:38 UTC
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
d39d714969cda5cbda291402c8c6b1fb1047f42e , < 694b0cee7f8546b69a80996a29cb3cf4149c0453
(git)
Affected: d39d714969cda5cbda291402c8c6b1fb1047f42e , < d0d520c19e7ea19ed38dc5797b12397b6ccf9f88 (git) Affected: d39d714969cda5cbda291402c8c6b1fb1047f42e , < dab4677bdbffa5c8270e79e34e51c89efa0728a0 (git) Affected: d39d714969cda5cbda291402c8c6b1fb1047f42e , < d5ef190693a7d76c5c192d108e8dec48307b46ee (git) |
guessed | |
| Linux | Linux |
Affected:
5.3
Unaffected: 0 , < 5.3 (semver) Unaffected: 5.4.151 , ≤ 5.4.* (semver) Unaffected: 5.10.71 , ≤ 5.10.* (semver) Unaffected: 5.14.10 , ≤ 5.14.* (semver) Unaffected: 5.15 , ≤ * (original_commit_for_fix) |
guessed |
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sched: flower: protect fl_walk() with rcu\n\nPatch that refactored fl_walk() to use idr_for_each_entry_continue_ul()\nalso removed rcu protection of individual filters which causes following\nuse-after-free when filter is deleted concurrently. Fix fl_walk() to obtain\nrcu read lock while iterating and taking the filter reference and temporary\nrelease the lock while calling arg-\u003efn() callback that can sleep.\n\nKASAN trace:\n\n[ 352.773640] ==================================================================\n[ 352.775041] BUG: KASAN: use-after-free in fl_walk+0x159/0x240 [cls_flower]\n[ 352.776304] Read of size 4 at addr ffff8881c8251480 by task tc/2987\n\n[ 352.777862] CPU: 3 PID: 2987 Comm: tc Not tainted 5.15.0-rc2+ #2\n[ 352.778980] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014\n[ 352.781022] Call Trace:\n[ 352.781573] dump_stack_lvl+0x46/0x5a\n[ 352.782332] print_address_description.constprop.0+0x1f/0x140\n[ 352.783400] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.784292] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.785138] kasan_report.cold+0x83/0xdf\n[ 352.785851] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.786587] kasan_check_range+0x145/0x1a0\n[ 352.787337] fl_walk+0x159/0x240 [cls_flower]\n[ 352.788163] ? fl_put+0x10/0x10 [cls_flower]\n[ 352.789007] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.790102] tcf_chain_dump+0x231/0x450\n[ 352.790878] ? tcf_chain_tp_delete_empty+0x170/0x170\n[ 352.791833] ? __might_sleep+0x2e/0xc0\n[ 352.792594] ? tfilter_notify+0x170/0x170\n[ 352.793400] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.794477] tc_dump_tfilter+0x385/0x4b0\n[ 352.795262] ? tc_new_tfilter+0x1180/0x1180\n[ 352.796103] ? __mod_node_page_state+0x1f/0xc0\n[ 352.796974] ? __build_skb_around+0x10e/0x130\n[ 352.797826] netlink_dump+0x2c0/0x560\n[ 352.798563] ? netlink_getsockopt+0x430/0x430\n[ 352.799433] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.800542] __netlink_dump_start+0x356/0x440\n[ 352.801397] rtnetlink_rcv_msg+0x3ff/0x550\n[ 352.802190] ? tc_new_tfilter+0x1180/0x1180\n[ 352.802872] ? rtnl_calcit.isra.0+0x1f0/0x1f0\n[ 352.803668] ? tc_new_tfilter+0x1180/0x1180\n[ 352.804344] ? _copy_from_iter_nocache+0x800/0x800\n[ 352.805202] ? kasan_set_track+0x1c/0x30\n[ 352.805900] netlink_rcv_skb+0xc6/0x1f0\n[ 352.806587] ? rht_deferred_worker+0x6b0/0x6b0\n[ 352.807455] ? rtnl_calcit.isra.0+0x1f0/0x1f0\n[ 352.808324] ? netlink_ack+0x4d0/0x4d0\n[ 352.809086] ? netlink_deliver_tap+0x62/0x3d0\n[ 352.809951] netlink_unicast+0x353/0x480\n[ 352.810744] ? netlink_attachskb+0x430/0x430\n[ 352.811586] ? __alloc_skb+0xd7/0x200\n[ 352.812349] netlink_sendmsg+0x396/0x680\n[ 352.813132] ? netlink_unicast+0x480/0x480\n[ 352.813952] ? __import_iovec+0x192/0x210\n[ 352.814759] ? netlink_unicast+0x480/0x480\n[ 352.815580] sock_sendmsg+0x6c/0x80\n[ 352.816299] ____sys_sendmsg+0x3a5/0x3c0\n[ 352.817096] ? kernel_sendmsg+0x30/0x30\n[ 352.817873] ? __ia32_sys_recvmmsg+0x150/0x150\n[ 352.818753] ___sys_sendmsg+0xd8/0x140\n[ 352.819518] ? sendmsg_copy_msghdr+0x110/0x110\n[ 352.820402] ? ___sys_recvmsg+0xf4/0x1a0\n[ 352.821110] ? __copy_msghdr_from_user+0x260/0x260\n[ 352.821934] ? _raw_spin_lock+0x81/0xd0\n[ 352.822680] ? __handle_mm_fault+0xef3/0x1b20\n[ 352.823549] ? rb_insert_color+0x2a/0x270\n[ 352.824373] ? copy_page_range+0x16b0/0x16b0\n[ 352.825209] ? perf_event_update_userpage+0x2d0/0x2d0\n[ 352.826190] ? __fget_light+0xd9/0xf0\n[ 352.826941] __sys_sendmsg+0xb3/0x130\n[ 352.827613] ? __sys_sendmsg_sock+0x20/0x20\n[ 352.828377] ? do_user_addr_fault+0x2c5/0x8a0\n[ 352.829184] ? fpregs_assert_state_consistent+0x52/0x60\n[ 352.830001] ? exit_to_user_mode_prepare+0x32/0x160\n[ 352.830845] do_syscall_64+0x35/0x80\n[ 352.831445] entry_SYSCALL_64_after_hwframe+0x44/0xae\n[ 352.832331] RIP: 0033:0x7f7bee973c17\n[ \n---truncated---"
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is triggered through local rtnetlink/tc syscalls (sendmsg \u2192 rtnetlink_rcv_msg \u2192 tc_dump_tfilter/tc_del_tfilter \u2192 fl_walk), not via remotely processed packets.\nAC:L - The attacker controls both sides of the race by concurrently dumping and deleting flower filters they created; flower is TCF_PROTO_OPS_DOIT_UNLOCKED so dump and delete can run without full rtnl serialization.\nPR:L - Creating/deleting filters requires CAP_NET_ADMIN via netlink_net_capable, which an unprivileged user obtains in a user+net namespace (unshare -Urn); tc/qdisc in userns is PR:L per guidance.\nUI:N - Exploitation requires only the attacker\u2019s own netlink operations; no victim action is needed.\nS:U - Impact is confined to the local kernel privilege boundary (standard local privilege escalation/DoS); it does not cross VM, IOMMU, or other security authorities.\nC:H - This is a use-after-free of a kmalloc-2k cls_fl_filter; UAF enables reclaim/spray of the freed object and arbitrary read primitives, including via the dump callback path.\nI:H - UAF of the filter object enables heap spraying and write/control-flow hijacking primitives once the freed slot is reclaimed with attacker-controlled data.\nA:H - The UAF produces a kernel oops/KASAN use-after-free (confirmed in the fix commit trace) and can crash or hang the system even without full exploitation."
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"title": "net: sched: flower: protect fl_walk() with rcu",
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"cveId": "CVE-2021-47402",
"datePublished": "2024-05-21T15:03:56.690Z",
"dateReserved": "2024-05-21T14:58:30.816Z",
"dateUpdated": "2026-08-05T08:47:42.173Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2021-47402",
"date": "2026-11-09",
"epss": "0.00246",
"percentile": "0.15965"
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"nvd": {
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sched: flower: protect fl_walk() with rcu\n\nPatch that refactored fl_walk() to use idr_for_each_entry_continue_ul()\nalso removed rcu protection of individual filters which causes following\nuse-after-free when filter is deleted concurrently. Fix fl_walk() to obtain\nrcu read lock while iterating and taking the filter reference and temporary\nrelease the lock while calling arg-\u003efn() callback that can sleep.\n\nKASAN trace:\n\n[ 352.773640] ==================================================================\n[ 352.775041] BUG: KASAN: use-after-free in fl_walk+0x159/0x240 [cls_flower]\n[ 352.776304] Read of size 4 at addr ffff8881c8251480 by task tc/2987\n\n[ 352.777862] CPU: 3 PID: 2987 Comm: tc Not tainted 5.15.0-rc2+ #2\n[ 352.778980] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014\n[ 352.781022] Call Trace:\n[ 352.781573] dump_stack_lvl+0x46/0x5a\n[ 352.782332] print_address_description.constprop.0+0x1f/0x140\n[ 352.783400] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.784292] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.785138] kasan_report.cold+0x83/0xdf\n[ 352.785851] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.786587] kasan_check_range+0x145/0x1a0\n[ 352.787337] fl_walk+0x159/0x240 [cls_flower]\n[ 352.788163] ? fl_put+0x10/0x10 [cls_flower]\n[ 352.789007] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.790102] tcf_chain_dump+0x231/0x450\n[ 352.790878] ? tcf_chain_tp_delete_empty+0x170/0x170\n[ 352.791833] ? __might_sleep+0x2e/0xc0\n[ 352.792594] ? tfilter_notify+0x170/0x170\n[ 352.793400] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.794477] tc_dump_tfilter+0x385/0x4b0\n[ 352.795262] ? tc_new_tfilter+0x1180/0x1180\n[ 352.796103] ? __mod_node_page_state+0x1f/0xc0\n[ 352.796974] ? __build_skb_around+0x10e/0x130\n[ 352.797826] netlink_dump+0x2c0/0x560\n[ 352.798563] ? netlink_getsockopt+0x430/0x430\n[ 352.799433] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.800542] __netlink_dump_start+0x356/0x440\n[ 352.801397] rtnetlink_rcv_msg+0x3ff/0x550\n[ 352.802190] ? tc_new_tfilter+0x1180/0x1180\n[ 352.802872] ? rtnl_calcit.isra.0+0x1f0/0x1f0\n[ 352.803668] ? tc_new_tfilter+0x1180/0x1180\n[ 352.804344] ? _copy_from_iter_nocache+0x800/0x800\n[ 352.805202] ? kasan_set_track+0x1c/0x30\n[ 352.805900] netlink_rcv_skb+0xc6/0x1f0\n[ 352.806587] ? rht_deferred_worker+0x6b0/0x6b0\n[ 352.807455] ? rtnl_calcit.isra.0+0x1f0/0x1f0\n[ 352.808324] ? netlink_ack+0x4d0/0x4d0\n[ 352.809086] ? netlink_deliver_tap+0x62/0x3d0\n[ 352.809951] netlink_unicast+0x353/0x480\n[ 352.810744] ? netlink_attachskb+0x430/0x430\n[ 352.811586] ? __alloc_skb+0xd7/0x200\n[ 352.812349] netlink_sendmsg+0x396/0x680\n[ 352.813132] ? netlink_unicast+0x480/0x480\n[ 352.813952] ? __import_iovec+0x192/0x210\n[ 352.814759] ? netlink_unicast+0x480/0x480\n[ 352.815580] sock_sendmsg+0x6c/0x80\n[ 352.816299] ____sys_sendmsg+0x3a5/0x3c0\n[ 352.817096] ? kernel_sendmsg+0x30/0x30\n[ 352.817873] ? __ia32_sys_recvmmsg+0x150/0x150\n[ 352.818753] ___sys_sendmsg+0xd8/0x140\n[ 352.819518] ? sendmsg_copy_msghdr+0x110/0x110\n[ 352.820402] ? ___sys_recvmsg+0xf4/0x1a0\n[ 352.821110] ? __copy_msghdr_from_user+0x260/0x260\n[ 352.821934] ? _raw_spin_lock+0x81/0xd0\n[ 352.822680] ? __handle_mm_fault+0xef3/0x1b20\n[ 352.823549] ? rb_insert_color+0x2a/0x270\n[ 352.824373] ? copy_page_range+0x16b0/0x16b0\n[ 352.825209] ? perf_event_update_userpage+0x2d0/0x2d0\n[ 352.826190] ? __fget_light+0xd9/0xf0\n[ 352.826941] __sys_sendmsg+0xb3/0x130\n[ 352.827613] ? __sys_sendmsg_sock+0x20/0x20\n[ 352.828377] ? do_user_addr_fault+0x2c5/0x8a0\n[ 352.829184] ? fpregs_assert_state_consistent+0x52/0x60\n[ 352.830001] ? exit_to_user_mode_prepare+0x32/0x160\n[ 352.830845] do_syscall_64+0x35/0x80\n[ 352.831445] entry_SYSCALL_64_after_hwframe+0x44/0xae\n[ 352.832331] RIP: 0033:0x7f7bee973c17\n[ \n---truncated---"
},
{
"lang": "es",
"value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: net: sched: flower: protege fl_walk() con rcu. El parche que refactoriz\u00f3 fl_walk() para usar idr_for_each_entry_continue_ul() tambi\u00e9n elimin\u00f3 la protecci\u00f3n de rcu de filtros individuales que provoca el siguiente use after free. cuando el filtro se elimina simult\u00e1neamente. Se corrige fl_walk() para obtener el bloqueo de lectura de rcu mientras se itera y se toma la referencia del filtro y se libera temporalmente el bloqueo mientras se llama a la devoluci\u00f3n de llamada arg-\u0026gt;fn() que puede dormir. Seguimiento de KASAN: [352.773640] ============================================= ========================== [352.775041] ERROR: KASAN: use-after-free en fl_walk+0x159/0x240 [cls_flower] [352.776304] Lectura de tama\u00f1o 4 en addr ffff8881c8251480 por tarea tc/2987 [ 352.777862] CPU: 3 PID: 2987 Comm: tc Not tainted 5.15.0-rc2+ #2 [ 352.778980] Nombre de hardware: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13 .0-0-gf21b5a4aeb02-prebuilt.qemu.org 01/04/2014 [352.781022] Seguimiento de llamadas: [352.781573] dump_stack_lvl+0x46/0x5a [352.782332] print_address_description.constprop.0+0x1f/0x140 [ 352.783400] ? fl_walk+0x159/0x240 [cls_flower] [ 352.784292] ? fl_walk+0x159/0x240 [cls_flower] [ 352.785138] kasan_report.cold+0x83/0xdf [ 352.785851] ? fl_walk+0x159/0x240 [cls_flower] [ 352.786587] kasan_check_range+0x145/0x1a0 [ 352.787337] fl_walk+0x159/0x240 [cls_flower] [ 352.788163] ? fl_put+0x10/0x10 [cls_flower] [ 352.789007] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220 [352.790102] tcf_chain_dump+0x231/0x450 [352.790878]? tcf_chain_tp_delete_empty+0x170/0x170 [352.791833]? __might_sleep+0x2e/0xc0 [ 352.792594] ? tfilter_notify+0x170/0x170 [352.793400]? __mutex_unlock_slowpath.constprop.0+0x220/0x220 [352.794477] tc_dump_tfilter+0x385/0x4b0 [352.795262]? tc_new_tfilter+0x1180/0x1180 [352.796103]? __mod_node_page_state+0x1f/0xc0 [352.796974]? __build_skb_around+0x10e/0x130 [ 352.797826] netlink_dump+0x2c0/0x560 [ 352.798563] ? netlink_getsockopt+0x430/0x430 [352.799433]? __mutex_unlock_slowpath.constprop.0+0x220/0x220 [ 352.800542] __netlink_dump_start+0x356/0x440 [ 352.801397] rtnetlink_rcv_msg+0x3ff/0x550 [ 352.802190] ? tc_new_tfilter+0x1180/0x1180 [352.802872]? rtnl_calcit.isra.0+0x1f0/0x1f0 [ 352.803668] ? tc_new_tfilter+0x1180/0x1180 [352.804344]? _copy_from_iter_nocache+0x800/0x800 [352.805202]? kasan_set_track+0x1c/0x30 [ 352.805900] netlink_rcv_skb+0xc6/0x1f0 [ 352.806587] ? rht_deferred_worker+0x6b0/0x6b0 [352.807455]? rtnl_calcit.isra.0+0x1f0/0x1f0 [352.808324]? netlink_ack+0x4d0/0x4d0 [352.809086]? netlink_deliver_tap+0x62/0x3d0 [352.809951] netlink_unicast+0x353/0x480 [352.810744]? netlink_attachskb+0x430/0x430 [352.811586]? __alloc_skb+0xd7/0x200 [ 352.812349] netlink_sendmsg+0x396/0x680 [ 352.813132] ? netlink_unicast+0x480/0x480 [352.813952]? __import_iovec+0x192/0x210 [352.814759]? netlink_unicast+0x480/0x480 [352.815580] sock_sendmsg+0x6c/0x80 [352.816299] ____sys_sendmsg+0x3a5/0x3c0 [352.817096] ? kernel_sendmsg+0x30/0x30 [352.817873]? __ia32_sys_recvmmsg+0x150/0x150 [ 352.818753] ___sys_sendmsg+0xd8/0x140 [ 352.819518] ? sendmsg_copy_msghdr+0x110/0x110 [352.820402]? ___sys_recvmsg+0xf4/0x1a0 [352.821110]? __copy_msghdr_from_user+0x260/0x260 [352.821934]? _raw_spin_lock+0x81/0xd0 [352.822680]? __handle_mm_fault+0xef3/0x1b20 [352.823549]? rb_insert_color+0x2a/0x270 [352.824373]? copy_page_range+0x16b0/0x16b0 [352.825209]? perf_event_update_userpage+0x2d0/0x2d0 [352.826190]? __fget_light+0xd9/0xf0 [ 352.826941] __sys_sendmsg+0xb3/0x130 [ 352.827613] ? __sys_sendmsg_sock+0x20/0x20 [352.828377]? do_user_addr_fault+0x2c5/0x8a0 [352.829184]? fpregs_assert_state_consistent+0x52/0x60 [352.830001]? exit_to_user_mode_prepare+0x32/0x160 [ 352.830845] do_syscall_64+0x35/0x80 [ 352.831445] Entry_SYSCALL_64_after_hwframe+0x44/0xae [ 352.832331] RIP: 0033:0x7f7bee973c1 7 [ ---truncado---"
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15",
"versionStartIncluding": "5.3",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sched: flower: protect fl_walk() with rcu\n\nPatch that refactored fl_walk() to use idr_for_each_entry_continue_ul()\nalso removed rcu protection of individual filters which causes following\nuse-after-free when filter is deleted concurrently. Fix fl_walk() to obtain\nrcu read lock while iterating and taking the filter reference and temporary\nrelease the lock while calling arg-\u003efn() callback that can sleep.\n\nKASAN trace:\n\n[ 352.773640] ==================================================================\n[ 352.775041] BUG: KASAN: use-after-free in fl_walk+0x159/0x240 [cls_flower]\n[ 352.776304] Read of size 4 at addr ffff8881c8251480 by task tc/2987\n\n[ 352.777862] CPU: 3 PID: 2987 Comm: tc Not tainted 5.15.0-rc2+ #2\n[ 352.778980] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014\n[ 352.781022] Call Trace:\n[ 352.781573] dump_stack_lvl+0x46/0x5a\n[ 352.782332] print_address_description.constprop.0+0x1f/0x140\n[ 352.783400] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.784292] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.785138] kasan_report.cold+0x83/0xdf\n[ 352.785851] ? fl_walk+0x159/0x240 [cls_flower]\n[ 352.786587] kasan_check_range+0x145/0x1a0\n[ 352.787337] fl_walk+0x159/0x240 [cls_flower]\n[ 352.788163] ? fl_put+0x10/0x10 [cls_flower]\n[ 352.789007] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.790102] tcf_chain_dump+0x231/0x450\n[ 352.790878] ? tcf_chain_tp_delete_empty+0x170/0x170\n[ 352.791833] ? __might_sleep+0x2e/0xc0\n[ 352.792594] ? tfilter_notify+0x170/0x170\n[ 352.793400] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.794477] tc_dump_tfilter+0x385/0x4b0\n[ 352.795262] ? tc_new_tfilter+0x1180/0x1180\n[ 352.796103] ? __mod_node_page_state+0x1f/0xc0\n[ 352.796974] ? __build_skb_around+0x10e/0x130\n[ 352.797826] netlink_dump+0x2c0/0x560\n[ 352.798563] ? netlink_getsockopt+0x430/0x430\n[ 352.799433] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220\n[ 352.800542] __netlink_dump_start+0x356/0x440\n[ 352.801397] rtnetlink_rcv_msg+0x3ff/0x550\n[ 352.802190] ? tc_new_tfilter+0x1180/0x1180\n[ 352.802872] ? rtnl_calcit.isra.0+0x1f0/0x1f0\n[ 352.803668] ? tc_new_tfilter+0x1180/0x1180\n[ 352.804344] ? _copy_from_iter_nocache+0x800/0x800\n[ 352.805202] ? kasan_set_track+0x1c/0x30\n[ 352.805900] netlink_rcv_skb+0xc6/0x1f0\n[ 352.806587] ? rht_deferred_worker+0x6b0/0x6b0\n[ 352.807455] ? rtnl_calcit.isra.0+0x1f0/0x1f0\n[ 352.808324] ? netlink_ack+0x4d0/0x4d0\n[ 352.809086] ? netlink_deliver_tap+0x62/0x3d0\n[ 352.809951] netlink_unicast+0x353/0x480\n[ 352.810744] ? netlink_attachskb+0x430/0x430\n[ 352.811586] ? __alloc_skb+0xd7/0x200\n[ 352.812349] netlink_sendmsg+0x396/0x680\n[ 352.813132] ? netlink_unicast+0x480/0x480\n[ 352.813952] ? __import_iovec+0x192/0x210\n[ 352.814759] ? netlink_unicast+0x480/0x480\n[ 352.815580] sock_sendmsg+0x6c/0x80\n[ 352.816299] ____sys_sendmsg+0x3a5/0x3c0\n[ 352.817096] ? kernel_sendmsg+0x30/0x30\n[ 352.817873] ? __ia32_sys_recvmmsg+0x150/0x150\n[ 352.818753] ___sys_sendmsg+0xd8/0x140\n[ 352.819518] ? sendmsg_copy_msghdr+0x110/0x110\n[ 352.820402] ? ___sys_recvmsg+0xf4/0x1a0\n[ 352.821110] ? __copy_msghdr_from_user+0x260/0x260\n[ 352.821934] ? _raw_spin_lock+0x81/0xd0\n[ 352.822680] ? __handle_mm_fault+0xef3/0x1b20\n[ 352.823549] ? rb_insert_color+0x2a/0x270\n[ 352.824373] ? copy_page_range+0x16b0/0x16b0\n[ 352.825209] ? perf_event_update_userpage+0x2d0/0x2d0\n[ 352.826190] ? __fget_light+0xd9/0xf0\n[ 352.826941] __sys_sendmsg+0xb3/0x130\n[ 352.827613] ? __sys_sendmsg_sock+0x20/0x20\n[ 352.828377] ? do_user_addr_fault+0x2c5/0x8a0\n[ 352.829184] ? fpregs_assert_state_consistent+0x52/0x60\n[ 352.830001] ? exit_to_user_mode_prepare+0x32/0x160\n[ 352.830845] do_syscall_64+0x35/0x80\n[ 352.831445] entry_SYSCALL_64_after_hwframe+0x44/0xae\n[ 352.832331] RIP: 0033:0x7f7bee973c17\n[ \n---truncated---"
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is triggered through local rtnetlink/tc syscalls (sendmsg \u2192 rtnetlink_rcv_msg \u2192 tc_dump_tfilter/tc_del_tfilter \u2192 fl_walk), not via remotely processed packets.\nAC:L - The attacker controls both sides of the race by concurrently dumping and deleting flower filters they created; flower is TCF_PROTO_OPS_DOIT_UNLOCKED so dump and delete can run without full rtnl serialization.\nPR:L - Creating/deleting filters requires CAP_NET_ADMIN via netlink_net_capable, which an unprivileged user obtains in a user+net namespace (unshare -Urn); tc/qdisc in userns is PR:L per guidance.\nUI:N - Exploitation requires only the attacker\u2019s own netlink operations; no victim action is needed.\nS:U - Impact is confined to the local kernel privilege boundary (standard local privilege escalation/DoS); it does not cross VM, IOMMU, or other security authorities.\nC:H - This is a use-after-free of a kmalloc-2k cls_fl_filter; UAF enables reclaim/spray of the freed object and arbitrary read primitives, including via the dump callback path.\nI:H - UAF of the filter object enables heap spraying and write/control-flow hijacking primitives once the freed slot is reclaimed with attacker-controlled data.\nA:H - The UAF produces a kernel oops/KASAN use-after-free (confirmed in the fix commit trace) and can crash or hang the system even without full exploitation."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T08:47:42.173Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/694b0cee7f8546b69a80996a29cb3cf4149c0453"
},
{
"url": "https://git.kernel.org/stable/c/d0d520c19e7ea19ed38dc5797b12397b6ccf9f88"
},
{
"url": "https://git.kernel.org/stable/c/dab4677bdbffa5c8270e79e34e51c89efa0728a0"
},
{
"url": "https://git.kernel.org/stable/c/d5ef190693a7d76c5c192d108e8dec48307b46ee"
}
],
"title": "net: sched: flower: protect fl_walk() with rcu",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2021-47402",
"datePublished": "2024-05-21T15:03:56.690Z",
"dateReserved": "2024-05-21T14:58:30.816Z",
"dateUpdated": "2026-08-05T08:47:42.173Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.