CVE-2026-46181: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event()

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-28 · updated 2026-10-30
Weakness: CWE-366

Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event() Sashiko points out the radix_tree itself is RCU safe, but nothing ever frees the mlx4_srq struct with RCU, and it isn't even accessed within the RCU critical section. It also will crash if an event is delivered before the srq object is finished initializing. Use the spinlock since it isn't easy to make RCU work, use refcount_inc_not_zero() to protect against partially initialized objects, and order the refcount_set() to be after the srq is fully initialized.

Affected products

Linux kernel: from 4.9 before 6.18.30; from 6.19 before 7.0.7; 7.1-rc1, 7.1-rc2 — fixed in 6.18.30, 7.0.7
Linux: 4.9 — fixed in 7.1

How to fix

Upgrade to a fixed version: Linux kernel 6.18.30, 7.0.7; Linux 7.1. Check the vendor advisory for mitigations.

References

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