---
id: CVE-2021-47012
title: |-
  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,..)
summary: |-
  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_ad…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.3, < 5.4.119'
  - 'linux_kernel >= 5.5, < 5.10.37'
  - 'linux_kernel >= 5.11, < 5.11.21'
  - 'linux_kernel >= 5.12, < 5.12.4'
patched:
  - linux_kernel 5.12.4
published: '2024-02-28'
updated: '2026-08-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-47012'
references:
  - url: 'https://git.kernel.org/stable/c/3093ee182f01689b89e9f8797b321603e5de4f63'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/30b9e92d0b5e5d5dc1101ab856c17009537cbca4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3e22b88e02c194f6c80867abfef5cc09383461f4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/608a4b90ece039940e9425ee2b39c8beff27e00c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ad9ce7188432650469a6c7625bf479f5ed0b6155'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3093ee182f01689b89e9f8797b321603e5de4f63'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/30b9e92d0b5e5d5dc1101ab856c17009537cbca4'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/3e22b88e02c194f6c80867abfef5cc09383461f4'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/608a4b90ece039940e9425ee2b39c8beff27e00c'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/ad9ce7188432650469a6c7625bf479f5ed0b6155'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00268
epssPercentile: 0.16833
ingestedAt: '2026-08-04T10:39:39.119Z'
---

## Overview

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

- `linux_kernel >= 5.3, < 5.4.119`
- `linux_kernel >= 5.5, < 5.10.37`
- `linux_kernel >= 5.11, < 5.11.21`
- `linux_kernel >= 5.12, < 5.12.4`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.12.4`