Linux Kernel up to 7.1.4 btrfs handle_reserve_tickets deadlock

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 7.1.4. The affected element is the function handle_reserve_tickets of the component btrfs. The manipulation results in deadlock. This vulnerability is cataloged as CVE-2026-74319. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.1.4. It has been classified as critical. Affected is the function handle_reserve_tickets of the component btrfs. The manipulation with an unknown input leads to a deadlock vulnerability. CWE is classifying the issue as CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: fix deadlock waiting for ticket during data relocation When performing data relocation on a zoned filesystem, BTRFS can deadlock in handle_reserve_tickets(). The relocation process is waiting on a space reservation ticket that can never be fulfilled, because the relocation itself is the operation responsible for freeing up that space. Fix this by introducing a new flush state, BTRFS_RESERVE_FLUSH_ZONED_RELOCATION, specifically for data chunk allocation during zoned relocation. Like BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE, this state uses priority_reclaim_data_space() instead of the normal flushing path, which avoids re-entering the relocation code and breaking the deadlock cycle. In btrfs_alloc_data_chunk_ondemand(), select this new flush state when the inode belongs to a data relocation root on a zoned filesystem.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-74319 since 08/15/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/15/2026). The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 7.1.5 or 7.2-rc1 eliminates this vulnerability. Applying the patch f84dbbaa988e1344634a20ddf6c7d51a99f12477 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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