CVE-2021-47334: misc/libmasm/module: Fix two use after free in ibmasm_init_one

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: 2024-05-21 · updated 2026-06-17
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: misc/libmasm/module: Fix two use after free in ibmasm_init_one In ibmasm_init_one, it calls ibmasm_init_remote_input_dev(). Inside ibmasm_init_remote_input_dev, mouse_dev and keybd_dev are allocated by input_allocate_device(), and assigned to sp->remote.mouse_dev and sp->remote.keybd_dev respectively. In the err_free_devices error branch of ibmasm_init_one, mouse_dev and keybd_dev are freed by input_free_device(), and return error. Then the execution runs into error_send_message error branch of ibmasm_init_one, where ibmasm_free_remote_input_dev(sp) is called to unregister the freed sp->remote.mouse_dev and sp->remote.keybd_dev. My patch add a "error_init_remote" label to handle the error of ibmasm_init_remote_input_dev(), to avoid the uaf bugs.

Affected products

Linux kernel: before 4.4.276; from 4.5 before 4.9.276; from 4.10 before 4.14.240; from 4.15 before 4.19.198; from 4.20 before 5.4.134; from 5.5 before 5.10.52 — fixed in 4.14.240, 4.19.198, 4.4.276, 4.9.276, 5.10.52, 5.12.19

How to fix

Upgrade to a fixed version: Linux kernel 4.14.240, 4.19.198, 4.4.276, 4.9.276. Check the vendor advisory for mitigations.

References

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