CVE-2024-42149 fs: don't misleadingly warn during thaw operations

What is CVE-2024-42149?

CVE-2024-42149 is a medium-severity vulnerability in Linux kernel, published on 30 Jul 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

fs: don't misleadingly warn during thaw operations

The block device may have been frozen before it was claimed by a filesystem. Concurrently another process might try to mount that frozen block device and has temporarily claimed the block device for that purpose causing a concurrent fs_bdev_thaw() to end up here. The mounter is already about to abort mounting because they still saw an elevanted bdev->bd_fsfreeze_count so get_bdev_super() will return NULL in that case.

For example, P1 calls dm_suspend() which calls into bdev_freeze() before the block device has been claimed by the filesystem. This brings bdev->bd_fsfreeze_count to 1 and no call into fs_bdev_freeze() is required.

Now P2 tries to mount that frozen block device. It claims it and checks bdev->bd_fsfreeze_count. As it's elevated it aborts mounting.

In the meantime P3 called dm_resume(). P3 sees that the block device is already claimed by a filesystem and calls into fs_bdev_thaw().

P3 takes a passive reference and realizes that the filesystem isn't ready yet. P3 puts itself to sleep to wait for the filesystem to become ready.

P2 now puts the last active reference to the filesystem and marks it as dying. P3 gets woken, sees that the filesystem is dying and get_bdev_super() fails.

Weakness: CWE-476

Which versions are affected by CVE-2024-42149?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-42149?

Apply the vendor's patch.

Is CVE-2024-42149 being exploited?

There is no known exploitation of CVE-2024-42149 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2024-42149, DEBIAN-CVE-2024-42149, GHSA-xggq-vrr8-pfwp, UBUNTU-CVE-2024-42149.