CVE-2024-49949

MEDIUM EPSS 19.4%
Published Oct 21, 20241y ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Oct 21, 2024 1y ago
Last Modified Jun 17, 2026 1w ago

Description

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---

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
19.4% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 10

VendorProductVersionRange
linuxlinux_kernel*≥4.14.256  –  <4.19
linuxlinux_kernel*≥4.19.218  –  <5.4
linuxlinux_kernel*≥5.4.162  –  <5.10
linuxlinux_kernel*≥5.10.82  –  <5.10.227
linuxlinux_kernel*≥5.15.5  –  <5.15.168
linuxlinux_kernel*≥5.16  –  <6.1.113
linuxlinux_kernel*≥6.2  –  <6.6.55
linuxlinux_kernel*≥6.7  –  <6.10.14
linuxlinux_kernel*≥6.11  –  <6.11.3
linuxlinux_kernel6.12any

References 14

  • cert-portal.siemens.com https://cert-portal.siemens.com/productcert/html/ssa-265688.html
  • cert-portal.siemens.com https://cert-portal.siemens.com/productcert/html/ssa-355557.html
  • cert-portal.siemens.com https://cert-portal.siemens.com/productcert/html/ssa-398330.html
  • git.kernel.org https://git.kernel.org/stable/c/1598d70ad9c7d0a4d9d54b82094e9f45908fda6d
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/25ab0b87dbd89cecef8a9c60a02bb97832e471d1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/81fd007dcd47c34471766249853e4d4bce8eea4b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/939c88cbdc668dadd8cfa7a35d9066331239041c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ba26060a29d3ca1bfc737aa79f7125128f35147c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c20029db28399ecc50e556964eaba75c43b1e2f1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d6114993e0a89fde84a60a60a8329a571580b174
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d70ca7598943572d5e384227bd268acb5109bf72
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f959cce8a2a04ce776aa8b78e83ce339e0d7fbac
    Patch
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/1598d70ad9c7d0a4d9d54b82094e9f45908fda6d
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/25ab0b87dbd89cecef8a9c60a02bb97832e471d1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/81fd007dcd47c34471766249853e4d4bce8eea4b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/939c88cbdc668dadd8cfa7a35d9066331239041c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ba26060a29d3ca1bfc737aa79f7125128f35147c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c20029db28399ecc50e556964eaba75c43b1e2f1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d6114993e0a89fde84a60a60a8329a571580b174
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d70ca7598943572d5e384227bd268acb5109bf72
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f959cce8a2a04ce776aa8b78e83ce339e0d7fbac
    Patch