In the Linux kernel, the following vulnerability has been resolved: net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd() In tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points directly into the mmap'd TX ring buffer shared with userspace. The kernel validates the header via __packet_snd_vnet_parse() but then re-reads all fields later in virtio_net_hdr_to_skb(). A concurrent userspace thread can modify the vnet_hdr fields between validation and use, bypassing all safety checks. The non-TPACKET path (packet_snd()) already correctly copies vnet_hdr to a stack-local variable. All other vnet_hdr consumers in the kernel (tun.c, tap.c, virtio_net.c) also use stack copies. The TPACKET TX path is the only caller of virtio_net_hdr_to_skb() that reads directly from user-controlled shared memory. Fix this by copying vnet_hdr from the mmap'd ring buffer to a stack-local variable before validation and use, consistent with the approach used in packet_snd() and all other callers.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | HIGH |
| Integrity Impact | HIGH |
| Availability Impact | HIGH |
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Type: Secondary
Exploitability Score: 1.8
Impact Score: 5.9
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-362
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x7d23a59c9c40> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7d23a59c9600> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7d239fbeb940> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7d239fbeb7c0> | Operating System |
| linux | linux_kernel | 7.1 | <built-in method update of dict object at 0x7d239fbeb500> | Operating System |
| linux | linux_kernel | 7.1 | <built-in method update of dict object at 0x7d239fbeb380> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* |