CVE-2026-80837
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: don't queue packet path object notifications All file:line references below are against v7.2-rc4 (ac5b0e5651b1). The trace was captured on 7.2.0-rc6-kasan72rc6 (075b74841bd0), where the same lines apply. nft_obj_notify() is exported and reached from the packet path. Its only in-tree caller is nft_quota_obj_eval() (net/netfilter/nft_quota.c:68), which notifies with GFP_ATOMIC while evaluating a rule for a transiting packet, holding no mutex. Since commit 67cc570edaa0 ("netfilter: nf_tables: coalesce multiple notifications into one skbuff") that notification is no longer sent immediately. __nft_obj_notify() queues it onto nft_net->notify_list via nft_notify_enqueue() (net/netfilter/nf_tables_api.c:1211), which is a bare list_add_tail(). notify_list has no lock of its own (include/net/netfilter/nf_tables.h:1951), it is serialised by commit_mutex: the six other enqueue sites all run inside a netlink transaction, and the drain in nft_commit_notify() (net/netfilter/nf_tables_api.c:10746) does list_del() + kfree_skb() from nf_tables_commit() with commit_mutex held. Sending packets through a chain that references a depleted quota object therefore races an unlocked list_add_tail() against list_del() + kfree_skb() on another CPU. The WRITE_ONCE(prev->next, new) in __list_add() then stores through an sk_buff that has already been freed: BUG: KASAN: slab-use-after-free in __nft_obj_notify+0x2c5/0x2d0 Write of size 8 at addr ff110001047183c0 by task poc/76 CPU: 0 UID: 1000 PID: 76 Comm: poc Tainted: G W 7.2.0-rc6-kasan72rc6 #4 Call Trace: <IRQ> __nft_obj_notify (include/linux/list.h:164 include/linux/list.h:191 net/netfilter/nf_tables_api.c:1211 net/netfilter/nf_tables_api.c:8743) nft_quota_obj_eval (net/netfilter/nft_quota.c:68) nft_do_chain_inet nf_hook_slow __ip_local_out ip_push_pending_frames udp_send_skb udp_sendmsg __x64_sys_sendto Allocated by task 77: __alloc_skb (net/core/skbuff.c:704) __nft_obj_notify (include/net/netlink.h:1055 net/netfilter/nf_tables_api.c:8731) nft_quota_obj_eval (net/netfilter/nft_quota.c:68) nft_do_chain Freed by task 79: nf_tables_commit (include/linux/skbuff.h:1332 net/netfilter/nf_tables_api.c:10759 net/netfilter/nf_tables_api.c:11185) nfnetlink_rcv_batch (net/netfilter/nfnetlink.c:574) netlink_unicast netlink_sendmsg The buggy address belongs to the cache skbuff_head_cache of size 232 Queueing from the packet path is wrong even leaving the race aside: notify_list is only drained by nft_commit_notify() from nf_tables_commit() (:11185), so a notification enqueued outside a transaction is not sent until some later netlink batch commits, if one ever does. The gfp argument that nft_obj_notify() still takes is a leftover of the pre-67cc570edaa0 behaviour, where this path called nfnetlink_send() directly. Restore that: split the message construction out into nft_obj_notify_alloc() and let each caller decide what to do with the skb. nft_obj_notify(), the exported one reached from the packet path, sends it straight away; nf_tables_obj_notify(), which runs under commit_mutex, keeps queueing it, so transaction notifications are still coalesced.
View original CVE JSON
{
"id": "CVE-2026-80837",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-04T16:18:12.030",
"lastModified": "2026-10-30T13:20:11.983",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: don't queue packet path object notifications\n\nAll file:line references below are against v7.2-rc4 (ac5b0e5651b1). The\ntrace was captured on 7.2.0-rc6-kasan72rc6 (075b74841bd0), where the same\nlines apply.\n\nnft_obj_notify() is exported and reached from the packet path. Its only\nin-tree caller is nft_quota_obj_eval() (net/netfilter/nft_quota.c:68),\nwhich notifies with GFP_ATOMIC while evaluating a rule for a transiting\npacket, holding no mutex.\n\nSince commit 67cc570edaa0 (\"netfilter: nf_tables: coalesce multiple\nnotifications into one skbuff\") that notification is no longer sent\nimmediately. __nft_obj_notify() queues it onto nft_net->notify_list via\nnft_notify_enqueue() (net/netfilter/nf_tables_api.c:1211), which is a bare\nlist_add_tail(). notify_list has no lock of its own\n(include/net/netfilter/nf_tables.h:1951), it is serialised by commit_mutex:\nthe six other enqueue sites all run inside a netlink transaction, and the\ndrain in nft_commit_notify() (net/netfilter/nf_tables_api.c:10746) does\nlist_del() + kfree_skb() from nf_tables_commit() with commit_mutex held.\n\nSending packets through a chain that references a depleted quota object\ntherefore races an unlocked list_add_tail() against list_del() +\nkfree_skb() on another CPU. The WRITE_ONCE(prev->next, new) in __list_add()\nthen stores through an sk_buff that has already been freed:\n\n BUG: KASAN: slab-use-after-free in __nft_obj_notify+0x2c5/0x2d0\n Write of size 8 at addr ff110001047183c0 by task poc/76\n CPU: 0 UID: 1000 PID: 76 Comm: poc Tainted: G W 7.2.0-rc6-kasan72rc6 #4\n Call Trace:\n <IRQ>\n __nft_obj_notify (include/linux/list.h:164 include/linux/list.h:191\n net/netfilter/nf_tables_api.c:1211\n net/netfilter/nf_tables_api.c:8743)\n nft_quota_obj_eval (net/netfilter/nft_quota.c:68)\n nft_do_chain_inet\n nf_hook_slow\n __ip_local_out\n ip_push_pending_frames\n udp_send_skb\n udp_sendmsg\n __x64_sys_sendto\n\n Allocated by task 77:\n __alloc_skb (net/core/skbuff.c:704)\n __nft_obj_notify (include/net/netlink.h:1055\n net/netfilter/nf_tables_api.c:8731)\n nft_quota_obj_eval (net/netfilter/nft_quota.c:68)\n nft_do_chain\n\n Freed by task 79:\n nf_tables_commit (include/linux/skbuff.h:1332\n net/netfilter/nf_tables_api.c:10759\n net/netfilter/nf_tables_api.c:11185)\n nfnetlink_rcv_batch (net/netfilter/nfnetlink.c:574)\n netlink_unicast\n netlink_sendmsg\n\n The buggy address belongs to the cache skbuff_head_cache of size 232\n\nQueueing from the packet path is wrong even leaving the race aside:\nnotify_list is only drained by nft_commit_notify() from nf_tables_commit()\n(:11185), so a notification enqueued outside a transaction is not sent\nuntil some later netlink batch commits, if one ever does.\n\nThe gfp argument that nft_obj_notify() still takes is a leftover of the\npre-67cc570edaa0 behaviour, where this path called nfnetlink_send()\ndirectly. Restore that: split the message construction out into\nnft_obj_notify_alloc() and let each caller decide what to do with the skb.\nnft_obj_notify(), the exported one reached from the packet path, sends it\nstraight away; nf_tables_obj_notify(), which runs under commit_mutex, keeps\nqueueing it, so transaction notifications are still coalesced."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/netfilter/nf_tables_api.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "67cc570edaa02016a8685a06a0ee91f05a6277d9",
"lessThan": "f010756ed75ac003146a1cbc93501092343bb3a3",
"versionType": "git",
"status": "affected"
},
{
"version": "67cc570edaa02016a8685a06a0ee91f05a6277d9",
"lessThan": "6989f298103f575a768a85e4b19d2384709237f8",
"versionType": "git",
"status": "affected"
},
{
"version": "67cc570edaa02016a8685a06a0ee91f05a6277d9",
"lessThan": "df86c0e84025be8b6dd572a20852698927aa666b",
"versionType": "git",
"status": "affected"
},
{
"version": "67cc570edaa02016a8685a06a0ee91f05a6277d9",
"lessThan": "6fa88d11983c6fe693c13ed7c5b3b75ae9f39de6",
"versionType": "git",
"status": "affected"
},
{
"version": "67cc570edaa02016a8685a06a0ee91f05a6277d9",
"lessThan": "e97e2d6d0b150fd78be573f9fdf193f204d9334e",
"versionType": "git",
"status": "affected"
},
{
"version": "67cc570edaa02016a8685a06a0ee91f05a6277d9",
"lessThan": "68de7f3a38acab355c24114f77bf00d3094ce4da",
"versionType": "git",
"status": "affected"
},
{
"version": "67cc570edaa02016a8685a06a0ee91f05a6277d9",
"lessThan": "7904b94768e983bcb2be34a8d6d1f3450f5b838b",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"net/netfilter/nf_tables_api.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "5.9",
"status": "affected"
},
{
"version": "0",
"lessThan": "5.9",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.191",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.158",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.108",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.49",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.1.13",
"lessThanOrEqual": "7.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.3",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/68de7f3a38acab355c24114f77bf00d3094ce4da",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/6989f298103f575a768a85e4b19d2384709237f8",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/6fa88d11983c6fe693c13ed7c5b3b75ae9f39de6",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/7904b94768e983bcb2be34a8d6d1f3450f5b838b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/df86c0e84025be8b6dd572a20852698927aa666b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e97e2d6d0b150fd78be573f9fdf193f204d9334e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f010756ed75ac003146a1cbc93501092343bb3a3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}