2025-03-09 03:03:50 +00:00

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{
"id": "CVE-2024-57974",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-02-27T02:15:10.590",
"lastModified": "2025-02-27T02:15:10.590",
"vulnStatus": "Awaiting Analysis",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nudp: Deal with race between UDP socket address change and rehash\n\nIf a UDP socket changes its local address while it's receiving\ndatagrams, as a result of connect(), there is a period during which\na lookup operation might fail to find it, after the address is changed\nbut before the secondary hash (port and address) and the four-tuple\nhash (local and remote ports and addresses) are updated.\n\nSecondary hash chains were introduced by commit 30fff9231fad (\"udp:\nbind() optimisation\") and, as a result, a rehash operation became\nneeded to make a bound socket reachable again after a connect().\n\nThis operation was introduced by commit 719f835853a9 (\"udp: add\nrehash on connect()\") which isn't however a complete fix: the\nsocket will be found once the rehashing completes, but not while\nit's pending.\n\nThis is noticeable with a socat(1) server in UDP4-LISTEN mode, and a\nclient sending datagrams to it. After the server receives the first\ndatagram (cf. _xioopen_ipdgram_listen()), it issues a connect() to\nthe address of the sender, in order to set up a directed flow.\n\nNow, if the client, running on a different CPU thread, happens to\nsend a (subsequent) datagram while the server's socket changes its\naddress, but is not rehashed yet, this will result in a failed\nlookup and a port unreachable error delivered to the client, as\napparent from the following reproducer:\n\n LEN=$(($(cat /proc/sys/net/core/wmem_default) / 4))\n dd if=/dev/urandom bs=1 count=${LEN} of=tmp.in\n\n while :; do\n \ttaskset -c 1 socat UDP4-LISTEN:1337,null-eof OPEN:tmp.out,create,trunc &\n \tsleep 0.1 || sleep 1\n \ttaskset -c 2 socat OPEN:tmp.in UDP4:localhost:1337,shut-null\n \twait\n done\n\nwhere the client will eventually get ECONNREFUSED on a write()\n(typically the second or third one of a given iteration):\n\n 2024/11/13 21:28:23 socat[46901] E write(6, 0x556db2e3c000, 8192): Connection refused\n\nThis issue was first observed as a seldom failure in Podman's tests\nchecking UDP functionality while using pasta(1) to connect the\ncontainer's network namespace, which leads us to a reproducer with\nthe lookup error resulting in an ICMP packet on a tap device:\n\n LOCAL_ADDR=\"$(ip -j -4 addr show|jq -rM '.[] | .addr_info[0] | select(.scope == \"global\").local')\"\n\n while :; do\n \t./pasta --config-net -p pasta.pcap -u 1337 socat UDP4-LISTEN:1337,null-eof OPEN:tmp.out,create,trunc &\n \tsleep 0.2 || sleep 1\n \tsocat OPEN:tmp.in UDP4:${LOCAL_ADDR}:1337,shut-null\n \twait\n \tcmp tmp.in tmp.out\n done\n\nOnce this fails:\n\n tmp.in tmp.out differ: char 8193, line 29\n\nwe can finally have a look at what's going on:\n\n $ tshark -r pasta.pcap\n 1 0.000000 :: ? ff02::16 ICMPv6 110 Multicast Listener Report Message v2\n 2 0.168690 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192\n 3 0.168767 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192\n 4 0.168806 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192\n 5 0.168827 c6:47:05:8d:dc:04 ? Broadcast ARP 42 Who has 88.198.0.161? Tell 88.198.0.164\n 6 0.168851 9a:55:9a:55:9a:55 ? c6:47:05:8d:dc:04 ARP 42 88.198.0.161 is at 9a:55:9a:55:9a:55\n 7 0.168875 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192\n 8 0.168896 88.198.0.164 ? 88.198.0.161 ICMP 590 Destination unreachable (Port unreachable)\n 9 0.168926 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192\n 10 0.168959 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192\n 11 0.168989 88.198.0.161 ? 88.198.0.164 UDP 4138 60260 ? 1337 Len=4096\n 12 0.169010 88.198.0.161 ? 88.198.0.164 UDP 42 60260 ? 1337 Len=0\n\nOn the third datagram received, the network namespace of the container\ninitiates an ARP lookup to deliver the ICMP message.\n\nIn another variant of this reproducer, starting the client with:\n\n strace -f pasta --config-net -u 1337 socat UDP4-LISTEN:1337,null-eof OPEN:tmp.out,create,tru\n---truncated---"
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: udp: lidiar con la ejecuci\u00f3n entre el cambio de direcci\u00f3n del socket UDP y el rehash Si un socket UDP cambia su direcci\u00f3n local mientras recibe datagramas, como resultado de connect(), hay un per\u00edodo durante el cual una operaci\u00f3n de b\u00fasqueda podr\u00eda fallar en encontrarlo, despu\u00e9s de que se cambie la direcci\u00f3n pero antes de que se actualicen el hash secundario (puerto y direcci\u00f3n) y el hash de cuatro tuplas (puertos y direcciones locales y remotos). Las cadenas de hash secundarias fueron introducidas por el commit 30fff9231fad (\"udp: optimizaci\u00f3n de bind()\") y, como resultado, se necesit\u00f3 una operaci\u00f3n de rehash para hacer que un socket enlazado sea accesible nuevamente despu\u00e9s de un connect(). Esta operaci\u00f3n fue introducida por el commit 719f835853a9 (\"udp: agregar rehash en connect()\") que, sin embargo, no es una soluci\u00f3n completa: el socket se encontrar\u00e1 una vez que se complete el rehash, pero no mientras est\u00e9 pendiente. Esto se nota con un servidor socat(1) en modo UDP4-LISTEN y un cliente que le env\u00eda datagramas. Despu\u00e9s de que el servidor recibe el primer datagrama (cf. _xioopen_ipdgram_listen()), emite un connect() a la direcci\u00f3n del remitente, para establecer un flujo dirigido. Ahora, si el cliente, que se ejecuta en un subproceso de CPU diferente, env\u00eda un datagrama (posterior) mientras el socket del servidor cambia su direcci\u00f3n, pero a\u00fan no se vuelve a procesar, esto dar\u00e1 como resultado una b\u00fasqueda fallida y un error de puerto inalcanzable entregado al cliente, como se desprende del siguiente reproductor: LEN=$(($(cat /proc/sys/net/core/wmem_default) / 4)) dd if=/dev/urandom bs=1 count=${LEN} of=tmp.in while :; do taskset -c 1 socat UDP4-LISTEN:1337,null-eof OPEN:tmp.out,create,trunc & sleep 0.1 || sleep 1 taskset -c 2 socat OPEN:tmp.in UDP4:localhost:1337,shut-null done donde el cliente eventualmente obtendr\u00e1 ECONNREFUSED en un write() (normalmente el segundo o tercero de una iteraci\u00f3n dada): 2024/11/13 21:28:23 socat[46901] E write(6, 0x556db2e3c000, 8192): Connection denied Este problema se observ\u00f3 por primera vez como una falla poco frecuente en las pruebas de Podman que verificaban la funcionalidad de UDP mientras se usaba pasta(1) para conectar el espacio de nombres de red del contenedor, lo que nos lleva a un reproductor con el error de b\u00fasqueda que resulta en un paquete ICMP en un dispositivo tap: LOCAL_ADDR=\"$(ip -j -4 addr show|jq -rM '.[] | .addr_info[0] | select(.scope == \"global\").local')\" while :; do ./pasta --config-net -p pasta.pcap -u 1337 socat UDP4-LISTEN:1337,null-eof OPEN:tmp.out,create,trunc & sleep 0.2 || sleep 1 socat OPEN:tmp.in UDP4:${LOCAL_ADDR}:1337,shut-null wait cmp tmp.in tmp.out done Once this fails: tmp.in tmp.out differ: char 8193, line 29 we can finally have a look at what's going on: $ tshark -r pasta.pcap 1 0.000000 :: ? ff02::16 ICMPv6 110 Multicast Listener Report Message v2 2 0.168690 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192 3 0.168767 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192 4 0.168806 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192 5 0.168827 c6:47:05:8d:dc:04 ? Broadcast ARP 42 Who has 88.198.0.161? Tell 88.198.0.164 6 0.168851 9a:55:9a:55:9a:55 ? c6:47:05:8d:dc:04 ARP 42 88.198.0.161 is at 9a:55:9a:55:9a:55 7 0.168875 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192 8 0.168896 88.198.0.164 ? 88.198.0.161 ICMP 590 Destination unreachable (Port unreachable) 9 0.168926 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192 10 0.168959 88.198.0.161 ? 88.198.0.164 UDP 8234 60260 ? 1337 Len=8192 11 0.168989 88.198.0.161 ? 88.198.0.164 UDP 4138 60260 ? 1337 Len=4096 12 0.169010 88.198.0.161 ? 88.198.0.164 UDP 42 60260 ? 1337 Len=0 On the third datagram received, the network namespace of the container initiates an ARP lookup to deliver the ICMP message. In another variant of this reproducer, starting the client with: strace -f pasta --config-net -u 1337 socat UDP4-LISTEN:1337,null-eof OPEN:tmp---truncada--- "
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/4f8344fce91c5766d368edb0ad80142eacd805c7",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a502ea6fa94b1f7be72a24bcf9e3f5f6b7e6e90c",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d65d3bf309b2649d27b24efd0d8784da2d81f2a6",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}