Linux Kernel, Use-After-Free Vulnerability, CVE-2025-37805 (Medium)

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How CVE-2025-37805 Works

This vulnerability occurs in the Linux kernel’s `virtio_snd` sound driver when handling error paths during initialization. The issue arises when `virtsnd_probe()` fails after allocating substreams but before initializing their `elapsed_period` work structures. When `virtsnd_remove()` is called during cleanup, it attempts to cancel uninitialized work_structs via cancel_work_sync(), triggering a kernel warning. The flaw stems from improper error handling, where allocated substreams are not fully initialized before a failure occurs, leading to a potential use-after-free scenario if the uninitialized work_structs are accessed.

DailyCVE Form:

Platform: Linux Kernel
Version: Pre-patch (ab15f34d0dd772f6d11327e08a81d46dc9c36276)
Vulnerability: Use-After-Free
Severity: Medium
Date: 06/05/2025

Prediction: Patch expected by 07/15/2025

What Undercode Say:

Exploitation Analysis:

  1. Trigger Condition: Malicious device emulation causing `virtsnd_probe()` to fail after substream allocation.
  2. Impact: Kernel warning/Oops, potential privilege escalation if combined with other bugs.

3. Debugging Command:

dmesg | grep "WARNING:.workqueue"

Protection Measures:

1. Patch Verification:

git grep "virtsnd_pcm_parse_cfg" /usr/src/linux

2. Temporary Mitigation: Disable `virtio_snd` module if unused:

echo "blacklist virtio_snd" >> /etc/modprobe.d/blacklist.conf

Code Snippet (Fix):

// Initialize work_struct immediately after allocation
for (i = 0; i < snd->nsubstreams; i++) {
INIT_WORK(&snd->substreams[bash].elapsed_period, virtsnd_pcm_elapsed_period);
}

CVSS 4.0 Vector:

CVSS:4.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References:

Monitoring Command:

watch -n 1 'cat /proc/modules | grep virtio_snd'

Sources:

Reported By: nvd.nist.gov
Extra Source Hub:
Undercode

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