CVE-2024-49949
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
net: avoid potential underflow in qdisc_pkt_len_init() with UFO
After commit 7c6d2ecbda83 ("net: be more gentle about silly gso requests coming from user") virtio_net_hdr_to_skb() had sanity check to detect malicious attempts from user space to cook a bad GSO packet.
Then commit cf9acc90c80ec ("net: virtio_net_hdr_to_skb: count transport header in UFO") while fixing one issue, allowed user space to cook a GSO packet with the following characteristic :
IPv4 SKB_GSO_UDP, gso_size=3, skb->len = 28.
When this packet arrives in qdisc_pkt_len_init(), we end up with hdr_len = 28 (IPv4 header + UDP header), matching skb->len
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Then the following sets gso_segs to 0 :
Then later we set qdisc_skb_cb(skb)->pkt_len to back to zero :/
This leads to the following crash in fq_codel [1]
qdisc_pkt_len_init() is best effort, we only want an estimation of the bytes sent on the wire, not crashing the kernel.
This patch is fixing this particular issue, a following one adds more sanity checks for another potential bug.
Detalles técnicos trazas, registros y código del informe original
gso_segs = DIV_ROUND_UP(skb->len - hdr_len,
shinfo->gso_size);
qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;
[1]
[ 70.724101] BUG: kernel NULL pointer dereference, address: 0000000000000000
[ 70.724561] #PF: supervisor read access in kernel mode
[ 70.724561] #PF: error_code(0x0000) - not-present page
[ 70.724561] PGD 10ac61067 P4D 10ac61067 PUD 107ee2067 PMD 0
[ 70.724561] Oops: Oops: 0000 [#1] SMP NOPTI
[ 70.724561] CPU: 11 UID: 0 PID: 2163 Comm: b358537762 Not tainted 6.11.0-virtme #991
[ 70.724561] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 70.724561] RIP: 0010:fq_codel_enqueue (net/sched/sch_fq_codel.c:120 net/sched/sch_fq_codel.c:168 net/sched/sch_fq_codel.c:230) sch_fq_codel
[ 70.724561] Code: 24 08 49 c1 e1 06 44 89 7c 24 18 45 31 ed 45 31 c0 31 ff 89 44 24 14 4c 03 8b 90 01 00 00 eb 04 39 ca 73 37 4d 8b 39 83 c7 01 <49> 8b 17 49 89 11 41 8b 57 28 45 8b 5f 34 49 c7 07 00 00 00 00 49
All code
========
0: 24 08 and $0x8,%al
2: 49 c1 e1 06 shl $0x6,%r9
6: 44 89 7c 24 18 mov %r15d,0x18(%rsp)
b: 45 31 ed xor %r13d,%r13d
e: 45 31 c0 xor %r8d,%r8d
11: 31 ff xor %edi,%edi
13: 89 44 24 14 mov %eax,0x14(%rsp)
17: 4c 03 8b 90 01 00 00 add 0x190(%rbx),%r9
1e: eb 04 jmp 0x24
20: 39 ca cmp %ecx,%edx
22: 73 37 jae 0x5b
24: 4d 8b 39 mov (%r9),%r15
27: 83 c7 01 add $0x1,%edi
2a:* 49 8b 17 mov (%r15),%rdx <-- trapping instruction
2d: 49 89 11 mov %rdx,(%r9)
30: 41 8b 57 28 mov 0x28(%r15),%edx
34: 45 8b 5f 34 mov 0x34(%r15),%r11d
38: 49 c7 07 00 00 00 00 movq $0x0,(%r15)
3f: 49 rex.WB
Code starting with the faulting instruction
===========================================
0: 49 8b 17 mov (%r15),%rdx
3: 49 89 11 mov %rdx,(%r9)
6: 41 8b 57 28 mov 0x28(%r15),%edx
a: 45 8b 5f 34 mov 0x34(%r15),%r11d
e: 49 c7 07 00 00 00 00 movq $0x0,(%r15)
15: 49 rex.WB
[ 70.724561] RSP: 0018:ffff95ae85e6fb90 EFLAGS: 00000202
[ 70.724561] RAX: 0000000002000000 RBX: ffff95ae841de000 RCX: 0000000000000000
[ 70.724561] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
[ 70.724561] RBP: ffff95ae85e6fbf8 R08: 0000000000000000 R09: ffff95b710a30000
[ 70.724561] R10: 0000000000000000 R11: bdf289445ce31881 R12: ffff95ae85e6fc58
[ 70.724561] R13: 0000000000000000 R14: 0000000000000040 R15: 0000000000000000
[ 70.724561] FS: 000000002c5c1380(0000) GS:ffff95bd7fcc0000(0000) knlGS:0000000000000000
[ 70.724561] CS: 0010 DS: 0000 ES: 0000 C
---truncated---CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.28%
- Percentil entre todas las CVEs puntuadas: 19
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- CWE-476
Referencias
- https://git.kernel.org/stable/c/1598d70ad9c7d0a4d9d54b82094e9f45908fda6d
- https://git.kernel.org/stable/c/25ab0b87dbd89cecef8a9c60a02bb97832e471d1
- https://git.kernel.org/stable/c/81fd007dcd47c34471766249853e4d4bce8eea4b
- https://git.kernel.org/stable/c/939c88cbdc668dadd8cfa7a35d9066331239041c
- https://git.kernel.org/stable/c/ba26060a29d3ca1bfc737aa79f7125128f35147c
- https://git.kernel.org/stable/c/c20029db28399ecc50e556964eaba75c43b1e2f1
- https://git.kernel.org/stable/c/d6114993e0a89fde84a60a60a8329a571580b174
- https://git.kernel.org/stable/c/d70ca7598943572d5e384227bd268acb5109bf72
- https://git.kernel.org/stable/c/f959cce8a2a04ce776aa8b78e83ce339e0d7fbac
- https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html
- https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html
- https://cert-portal.siemens.com/productcert/html/ssa-355557.html
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html
JSON original (NVD)
Mostrar
{
"id": "CVE-2024-49949",
"cveTags": [],
"metrics": {
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{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"role": "CISA Coordinator",
"options": [
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},
{
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},
{
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}
],
"version": "2.0.3",
"timestamp": "2024-10-22T13:36:39.259120Z"
}
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"attackVector": "LOCAL",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "NONE"
},
"impactScore": 3.6,
"exploitabilityScore": 1.8
}
]
},
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{
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{
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},
{
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},
{
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},
{
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],
"published": "2024-10-21T18:15:16.323",
"references": [
{
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"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html",
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-265688.html",
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-355557.html",
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-398330.html",
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
}
],
"vulnStatus": "Modified",
"weaknesses": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "CWE-476"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: avoid potential underflow in qdisc_pkt_len_init() with UFO\n\nAfter commit 7c6d2ecbda83 (\"net: be more gentle about silly gso\nrequests coming from user\") virtio_net_hdr_to_skb() had sanity check\nto detect malicious attempts from user space to cook a bad GSO packet.\n\nThen commit cf9acc90c80ec (\"net: virtio_net_hdr_to_skb: count\ntransport header in UFO\") while fixing one issue, allowed user space\nto cook a GSO packet with the following characteristic :\n\nIPv4 SKB_GSO_UDP, gso_size=3, skb->len = 28.\n\nWhen this packet arrives in qdisc_pkt_len_init(), we end up\nwith hdr_len = 28 (IPv4 header + UDP header), matching skb->len\n\nThen the following sets gso_segs to 0 :\n\ngso_segs = DIV_ROUND_UP(skb->len - hdr_len,\n shinfo->gso_size);\n\nThen later we set qdisc_skb_cb(skb)->pkt_len to back to zero :/\n\nqdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;\n\nThis leads to the following crash in fq_codel [1]\n\nqdisc_pkt_len_init() is best effort, we only want an estimation\nof the bytes sent on the wire, not crashing the kernel.\n\nThis patch is fixing this particular issue, a following one\nadds more sanity checks for another potential bug.\n\n[1]\n[ 70.724101] BUG: kernel NULL pointer dereference, address: 0000000000000000\n[ 70.724561] #PF: supervisor read access in kernel mode\n[ 70.724561] #PF: error_code(0x0000) - not-present page\n[ 70.724561] PGD 10ac61067 P4D 10ac61067 PUD 107ee2067 PMD 0\n[ 70.724561] Oops: Oops: 0000 [#1] SMP NOPTI\n[ 70.724561] CPU: 11 UID: 0 PID: 2163 Comm: b358537762 Not tainted 6.11.0-virtme #991\n[ 70.724561] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n[ 70.724561] RIP: 0010:fq_codel_enqueue (net/sched/sch_fq_codel.c:120 net/sched/sch_fq_codel.c:168 net/sched/sch_fq_codel.c:230) sch_fq_codel\n[ 70.724561] Code: 24 08 49 c1 e1 06 44 89 7c 24 18 45 31 ed 45 31 c0 31 ff 89 44 24 14 4c 03 8b 90 01 00 00 eb 04 39 ca 73 37 4d 8b 39 83 c7 01 <49> 8b 17 49 89 11 41 8b 57 28 45 8b 5f 34 49 c7 07 00 00 00 00 49\nAll code\n========\n 0:\t24 08 \tand $0x8,%al\n 2:\t49 c1 e1 06 \tshl $0x6,%r9\n 6:\t44 89 7c 24 18 \tmov %r15d,0x18(%rsp)\n b:\t45 31 ed \txor %r13d,%r13d\n e:\t45 31 c0 \txor %r8d,%r8d\n 11:\t31 ff \txor %edi,%edi\n 13:\t89 44 24 14 \tmov %eax,0x14(%rsp)\n 17:\t4c 03 8b 90 01 00 00 \tadd 0x190(%rbx),%r9\n 1e:\teb 04 \tjmp 0x24\n 20:\t39 ca \tcmp %ecx,%edx\n 22:\t73 37 \tjae 0x5b\n 24:\t4d 8b 39 \tmov (%r9),%r15\n 27:\t83 c7 01 \tadd $0x1,%edi\n 2a:*\t49 8b 17 \tmov (%r15),%rdx\t\t<-- trapping instruction\n 2d:\t49 89 11 \tmov %rdx,(%r9)\n 30:\t41 8b 57 28 \tmov 0x28(%r15),%edx\n 34:\t45 8b 5f 34 \tmov 0x34(%r15),%r11d\n 38:\t49 c7 07 00 00 00 00 \tmovq $0x0,(%r15)\n 3f:\t49 \trex.WB\n\nCode starting with the faulting instruction\n===========================================\n 0:\t49 8b 17 \tmov (%r15),%rdx\n 3:\t49 89 11 \tmov %rdx,(%r9)\n 6:\t41 8b 57 28 \tmov 0x28(%r15),%edx\n a:\t45 8b 5f 34 \tmov 0x34(%r15),%r11d\n e:\t49 c7 07 00 00 00 00 \tmovq $0x0,(%r15)\n 15:\t49 \trex.WB\n[ 70.724561] RSP: 0018:ffff95ae85e6fb90 EFLAGS: 00000202\n[ 70.724561] RAX: 0000000002000000 RBX: ffff95ae841de000 RCX: 0000000000000000\n[ 70.724561] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001\n[ 70.724561] RBP: ffff95ae85e6fbf8 R08: 0000000000000000 R09: ffff95b710a30000\n[ 70.724561] R10: 0000000000000000 R11: bdf289445ce31881 R12: ffff95ae85e6fc58\n[ 70.724561] R13: 0000000000000000 R14: 0000000000000040 R15: 0000000000000000\n[ 70.724561] FS: 000000002c5c1380(0000) GS:ffff95bd7fcc0000(0000) knlGS:0000000000000000\n[ 70.724561] CS: 0010 DS: 0000 ES: 0000 C\n---truncated---"
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net: evitar un posible desbordamiento en qdisc_pkt_len_init() con UFO Después de el commit 7c6d2ecbda83 (\"net: sea más cuidadoso con las solicitudes gso tontas que vienen del usuario\"), virtio_net_hdr_to_skb() tuvo una verificación de cordura para detectar intentos maliciosos desde el espacio del usuario de cocinar un paquete GSO defectuoso. Luego, confirma cf9acc90c80ec (\"net: virtio_net_hdr_to_skb: cuenta el encabezado de transporte en UFO\") mientras corrige un problema, permitió que el espacio de usuario cocinara un paquete GSO con la siguiente característica: IPv4 SKB_GSO_UDP, gso_size=3, skb->len = 28. Cuando este paquete llega a qdisc_pkt_len_init(), terminamos con hdr_len = 28 (encabezado IPv4 + encabezado UDP), que coincide con skb->len. Luego, lo siguiente establece gso_segs en 0: gso_segs = DIV_ROUND_UP(skb->len - hdr_len, shinfo->gso_size); Luego, configuramos qdisc_skb_cb(skb)->pkt_len nuevamente a cero :/ qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len; Esto genera el siguiente bloqueo en fq_codel [1] qdisc_pkt_len_init() es el mejor esfuerzo, solo queremos una estimación de los bytes enviados en la red, no bloquear el kernel. Este parche soluciona este problema en particular, el siguiente agrega más controles de cordura para otro error potencial. [1] [ 70.724101] ERROR: desreferencia de puntero NULL del núcleo, dirección: 0000000000000000 [ 70.724561] #PF: acceso de lectura del supervisor en modo núcleo [ 70.724561] #PF: error_code(0x0000) - página no presente [ 70.724561] PGD 10ac61067 P4D 10ac61067 PUD 107ee2067 PMD 0 [ 70.724561] Oops: Oops: 0000 [#1] SMP NOPTI [ 70.724561] CPU: 11 UID: 0 PID: 2163 Comm: b358537762 No contaminado 6.11.0-virtme #991 [ 70.724561] Nombre del hardware: PC estándar QEMU (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 01/04/2014 [ 70.724561] RIP: 0010:fq_codel_enqueue (net/sched/sch_fq_codel.c:120 net/sched/sch_fq_codel.c:168 net/sched/sch_fq_codel.c:230) sch_fq_codel [ 70.724561] Código: 24 08 49 c1 e1 06 44 89 7c 24 18 45 31 ed 45 31 c0 31 ff 89 44 24 14 4c 03 8b 90 01 00 00 eb 04 39 ca 73 37 4d 8b 39 83 c7 01 <49> 8b 17 49 89 11 41 8b 57 28 45 8b 5f 34 49 c7 07 00 00 00 00 49 Todo el código ======== 0: 24 08 y $0x8,%al 2: 49 c1 e1 06 shl $0x6,%r9 6: 44 89 7c 24 18 mov %r15d,0x18(%rsp) b: 45 31 ed xor %r13d,%r13d e: 45 31 c0 xor %r8d,%r8d 11: 31 ff xor %edi,%edi 13: 89 44 24 14 mov %eax,0x14(%rsp) 17: 4c 03 8b 90 01 00 00 suma 0x190(%rbx),%r9 1e: eb 04 jmp 0x24 20: 39 ca cmp %ecx,%edx 22: 73 37 jae 0x5b 24: 4d 8b 39 mov (%r9),%r15 27: 83 c7 01 suma $0x1,%edi 2a:* 49 8b 17 mov (%r15),%rdx <-- instrucción de captura 2d: 49 89 11 mov %rdx,(%r9) 30: 41 8b 57 28 mov 0x28(%r15),%edx 34: 45 8b 5f 34 mov 0x34(%r15),%r11d 38: 49 c7 07 00 00 00 00 movq $0x0,(%r15) 3f: 49 rex.WB Código que comienza con la instrucción que fallo ============================================= 0: 49 8b 17 mov (%r15),%rdx 3: 49 89 11 mov %rdx,(%r9) 6: 41 8b 57 28 mov 0x28(%r15),%edx a: 45 8b 5f 34 mov 0x34(%r15),%r11d e: 49 c7 07 00 00 00 00 movq $0x0,(%r15) 15: 49 rex.WB [ 70.724561] RSP: 0018:ffff95ae85e6fb90 EFLAGS: 00000202 [ 70.724561] RAX: 000000000200000 RBX: ffff95ae841de000 RCX: 0000000000000000 [ 70.724561] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00000000000000001 [ 70.724561] RBP: ffff95ae85e6fbf8 R08: 0000000000000000 R09: ffff95b710a30000 [ 70.724561] R10: 000000000000000 R11: bdf289445ce31881 R12: ffff95ae85e6fc58 [ 70.724561] R13: 000000000000000 R14: 0000000000000040 R15: 0000000000000000 [ 70.724561] FS: 000000002c5c1380(0000) GS:ffff95bd7fcc0000(0000) knlGS:0000000000000000 [ 70.724561] CS: 0010 DS: 0000 ES: 0000 C ---truncado---"
}
],
"lastModified": "2026-06-17T08:00:48.020",
"configurations": [
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