CVE-2021-47012: RDMA/siw: Fix a use after free in siw_alloc_mr

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-02-28 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/siw: Fix a use after free in siw_alloc_mr Our code analyzer reported a UAF. In siw_alloc_mr(), it calls siw_mr_add_mem(mr,..). In the implementation of siw_mr_add_mem(), mem is assigned to mr->mem and then mem is freed via kfree(mem) if xa_alloc_cyclic() failed. Here, mr->mem still point to a freed object. After, the execution continue up to the err_out branch of siw_alloc_mr, and the freed mr->mem is used in siw_mr_drop_mem(mr). My patch moves "mr->mem = mem" behind the if (xa_alloc_cyclic(..)<0) {} section, to avoid the uaf.

Affected products

Linux kernel: from 5.3 before 5.4.119; from 5.5 before 5.10.37; from 5.11 before 5.11.21; from 5.12 before 5.12.4 — fixed in 5.10.37, 5.11.21, 5.12.4, 5.4.119

How to fix

Upgrade to a fixed version: Linux kernel 5.10.37, 5.11.21, 5.12.4, 5.4.119. Check the vendor advisory for mitigations.

References

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