ghsa-4x74-8q36-fc3h
Vulnerability from github
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
Then the following sets gso_segs to 0 :
gso_segs = DIV_ROUND_UP(skb->len - hdr_len, shinfo->gso_size);
Then later we set qdisc_skb_cb(skb)->pkt_len to back to zero :/
qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;
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.
[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---
{
"affected": [],
"aliases": [
"CVE-2024-49949"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-21T18:15:16Z",
"severity": "MODERATE"
},
"details": "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-\u003elen = 28.\n\nWhen this packet arrives in qdisc_pkt_len_init(), we end up\nwith hdr_len = 28 (IPv4 header + UDP header), matching skb-\u003elen\n\nThen the following sets gso_segs to 0 :\n\ngso_segs = DIV_ROUND_UP(skb-\u003elen - hdr_len,\n shinfo-\u003egso_size);\n\nThen later we set qdisc_skb_cb(skb)-\u003epkt_len to back to zero :/\n\nqdisc_skb_cb(skb)-\u003epkt_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 \u003c49\u003e 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\u003c-- 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---",
"id": "GHSA-4x74-8q36-fc3h",
"modified": "2024-11-12T21:30:50Z",
"published": "2024-10-21T18:30:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-49949"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1598d70ad9c7d0a4d9d54b82094e9f45908fda6d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/25ab0b87dbd89cecef8a9c60a02bb97832e471d1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/81fd007dcd47c34471766249853e4d4bce8eea4b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/939c88cbdc668dadd8cfa7a35d9066331239041c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ba26060a29d3ca1bfc737aa79f7125128f35147c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c20029db28399ecc50e556964eaba75c43b1e2f1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d6114993e0a89fde84a60a60a8329a571580b174"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d70ca7598943572d5e384227bd268acb5109bf72"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f959cce8a2a04ce776aa8b78e83ce339e0d7fbac"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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- Confirmed: The vulnerability is confirmed from an analyst perspective.
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- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.