HIGH
net/smc LinkGroup Deref
CVE-2026-46027
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
KernelScan AI5.5MEDIUM
01Description
In the Linux kernel, the following vulnerability has been resolved: net/smc: avoid early lgr access in smc_clc_wait_msg A CLC decline can be received while the handshake is still in an early stage, before the connection has been associated with a link group. The decline handling in smc_clc_wait_msg() updates link-group level sync state for first-contact declines, but that state only exists after link group setup has completed. Guard the link-group update accordingly and keep the per-socket peer diagnosis handling unchanged. This preserves the existing sync_err handling for established link-group contexts and avoids touching link-group state before it is available.
02KernelScan AI Analysis
Risk summary
Local users with low privileges can trigger a kernel NULL pointer dereference in the SMC (Shared Memory Communications) protocol during connection handshake decline handling. This leads to a kernel panic and system unavailability, affecting systems that use SMC networking.
Vulnerability analysis
The vulnerability occurs in smc_clc_wait_msg() when handling CLC decline messages during SMC connection handshake. The original code unconditionally accesses smc->conn.lgr (link group) to update sync_err state for first-contact declines, but this pointer can be NULL if the decline is received before link group setup completes. The fix adds a NULL check (smc->conn.lgr) before accessing the link group structure, preventing the NULL pointer dereference while preserving existing sync error handling for established connections.
03Fix Versions
| Branch | Fixed in | Patch commit |
|---|---|---|
| 5.10 | 5.10.258 | 257cdf0c5ced |
| 5.15 | 5.15.209 | 22546729b96f |
| 6.1 | 6.1.175 | 5eedbfd82c28 |
| 6.12 | 6.12.86 | 6180a296ca65 |
| 6.18 | 6.18.27 | ea0b5d0fe963 |
| 6.6 | 6.6.140 | f0858e1d5624 |
| 7.0 | 7.0.4 | 83bcf9228b05 |
| mainline | 7.1-rc1 | 5a8db80f721d |