// For flags

CVE-2024-38538

net: bridge: xmit: make sure we have at least eth header len bytes

Severity Score

7.1
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

In the Linux kernel, the following vulnerability has been resolved:

net: bridge: xmit: make sure we have at least eth header len bytes

syzbot triggered an uninit value[1] error in bridge device's xmit path
by sending a short (less than ETH_HLEN bytes) skb. To fix it check if
we can actually pull that amount instead of assuming.

Tested with dropwatch:
drop at: br_dev_xmit+0xb93/0x12d0 [bridge] (0xffffffffc06739b3)
origin: software
timestamp: Mon May 13 11:31:53 2024 778214037 nsec
protocol: 0x88a8
length: 2
original length: 2
drop reason: PKT_TOO_SMALL

[1]
BUG: KMSAN: uninit-value in br_dev_xmit+0x61d/0x1cb0 net/bridge/br_device.c:65
br_dev_xmit+0x61d/0x1cb0 net/bridge/br_device.c:65
__netdev_start_xmit include/linux/netdevice.h:4903 [inline]
netdev_start_xmit include/linux/netdevice.h:4917 [inline]
xmit_one net/core/dev.c:3531 [inline]
dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3547
__dev_queue_xmit+0x34db/0x5350 net/core/dev.c:4341
dev_queue_xmit include/linux/netdevice.h:3091 [inline]
__bpf_tx_skb net/core/filter.c:2136 [inline]
__bpf_redirect_common net/core/filter.c:2180 [inline]
__bpf_redirect+0x14a6/0x1620 net/core/filter.c:2187
____bpf_clone_redirect net/core/filter.c:2460 [inline]
bpf_clone_redirect+0x328/0x470 net/core/filter.c:2432
___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
__bpf_prog_run512+0xb5/0xe0 kernel/bpf/core.c:2238
bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
__bpf_prog_run include/linux/filter.h:657 [inline]
bpf_prog_run include/linux/filter.h:664 [inline]
bpf_test_run+0x499/0xc30 net/bpf/test_run.c:425
bpf_prog_test_run_skb+0x14ea/0x1f20 net/bpf/test_run.c:1058
bpf_prog_test_run+0x6b7/0xad0 kernel/bpf/syscall.c:4269
__sys_bpf+0x6aa/0xd90 kernel/bpf/syscall.c:5678
__do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
__x64_sys_bpf+0xa0/0xe0 kernel/bpf/syscall.c:5765
x64_sys_call+0x96b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: net: bridge: xmit: asegúrese de tener al menos el encabezado eth len bytes syzbot desencadenó un error de valor uninit[1] en la ruta xmit del dispositivo puente al enviar un mensaje corto (menos de ETH_HLEN bytes) skb. Para solucionarlo, compruebe si realmente podemos retirar esa cantidad en lugar de suponerla. Probado con dropwatch: soltar en: br_dev_xmit+0xb93/0x12d0 [puente] (0xffffffffc06739b3) origen: marca de tiempo del software: lunes 13 de mayo 11:31:53 2024 778214037 protocolo nsec: 0x88a8 longitud: 2 longitud original: 2 motivo de caída: PKT_TOO_SMALL [1 ] ERROR: KMSAN: valor uninit en br_dev_xmit+0x61d/0x1cb0 net/bridge/br_device.c:65 br_dev_xmit+0x61d/0x1cb0 net/bridge/br_device.c:65 __netdev_start_xmit include/linux/netdevice.h:4903 [en línea] netdev_start_xmit include/linux/netdevice.h:4917 [en línea] xmit_one net/core/dev.c:3531 [en línea] dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3547 __dev_queue_xmit+0x34db/0x5350 net/core/dev .c:4341 dev_queue_xmit include/linux/netdevice.h:3091 [en línea] __bpf_tx_skb net/core/filter.c:2136 [en línea] __bpf_redirect_common net/core/filter.c:2180 [en línea] __bpf_redirect+0x14a6/0x1620 net/ Core/Filter.C: 2187 ____BPF_CLONE_REDIRECT NET/CORE/FILTRO.C: 2460 [Inline] BPF_CLONE_REDIRECT+0x328/0x470 NET/Core/Filter.c: 2432 ___ BPF_PROG_RUN+0X13FE/0XE0F0 KERNEL/BPF/BPF/CORE. 0xb5/0xe0 kernel/bpf/core.c:2238 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [en línea] __bpf_prog_run include/linux/filter.h:657 [en línea] bpf_prog_run include/linux/filter.h:664 [en línea ] bpf_test_run+0x499/0xc30 net/bpf/test_run.c:425 bpf_prog_test_run_skb+0x14ea/0x1f20 net/bpf/test_run.c:1058 bpf_prog_test_run+0x6b7/0xad0 kernel/bpf/syscall.c:4269 pf+0x6aa/0xd90 núcleo/ bpf/syscall.c:5678 __do_sys_bpf kernel/bpf/syscall.c:5767 [en línea] __se_sys_bpf kernel/bpf/syscall.c:5765 [en línea] __x64_sys_bpf+0xa0/0xe0 kernel/bpf/syscall.c:5765 ys_call+0x96b /0x3b50 arch/x86/include/generated/asm/syscalls_64.h:322 do_syscall_x64 arch/x86/entry/common.c:52 [en línea] do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 Entry_SYSCALL_64_after_hwframe+ 0x77/0x7f

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-06-18 CVE Reserved
  • 2024-06-19 CVE Published
  • 2024-08-29 EPSS Updated
  • 2024-11-05 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-99: Improper Control of Resource Identifiers ('Resource Injection')
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.12 < 6.1.93
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.1.93"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.12 < 6.6.33
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.6.33"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.12 < 6.8.12
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.8.12"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.12 < 6.9.3
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.9.3"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 2.6.12 < 6.10
Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.10"
en
Affected