In the Linux kernel, the following vulnerability has been resolved: btrfs: fix extent map leak in NOCOW direct I/O write btrfs_dio_iomap_begin()… (CVE-2026-89644)
A vulnerability in the Linux kernel's Btrfs filesystem was fixed involving an extent map leak during NOCOW direct I/O writes. The issue occurs when an error in allocating an ordered extent causes the function to return without properly releasing a reference to an extent map, potentially leading to resource leakage.
AI Analysis
Technical Summary
The vulnerability in the Linux kernel's Btrfs filesystem relates to improper handling of extent map references in the btrfs_dio_iomap_begin() function. Specifically, when performing direct writes into a NOCOW (No Copy-On-Write) range, if btrfs_create_dio_extent() fails (for example, due to failure in btrfs_alloc_ordered_extent()), the input extent map reference is not dropped, causing a leak. The fix involves checking the error from btrfs_create_dio_extent() before replacing the map and ensuring the input extent map is dropped on failure to prevent the leak.
Potential Impact
The vulnerability causes an extent map reference leak in the Btrfs filesystem during certain direct I/O write operations. This could lead to resource exhaustion or instability in the kernel due to unreleased references. There is no indication of code execution or privilege escalation from the provided data.
Mitigation Recommendations
A fix has been applied to the Linux kernel to properly drop the extent map reference on failure paths in the affected functions. Users should apply the official kernel updates that include this fix. No additional mitigation steps are indicated.
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix extent map leak in NOCOW direct I/O write btrfs_dio_iomap_begin()… (CVE-2026-89644)
Description
A vulnerability in the Linux kernel's Btrfs filesystem was fixed involving an extent map leak during NOCOW direct I/O writes. The issue occurs when an error in allocating an ordered extent causes the function to return without properly releasing a reference to an extent map, potentially leading to resource leakage.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in the Linux kernel's Btrfs filesystem relates to improper handling of extent map references in the btrfs_dio_iomap_begin() function. Specifically, when performing direct writes into a NOCOW (No Copy-On-Write) range, if btrfs_create_dio_extent() fails (for example, due to failure in btrfs_alloc_ordered_extent()), the input extent map reference is not dropped, causing a leak. The fix involves checking the error from btrfs_create_dio_extent() before replacing the map and ensuring the input extent map is dropped on failure to prevent the leak.
Potential Impact
The vulnerability causes an extent map reference leak in the Btrfs filesystem during certain direct I/O write operations. This could lead to resource exhaustion or instability in the kernel due to unreleased references. There is no indication of code execution or privilege escalation from the provided data.
Mitigation Recommendations
A fix has been applied to the Linux kernel to properly drop the extent map reference on failure paths in the affected functions. Users should apply the official kernel updates that include this fix. No additional mitigation steps are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-8844-3wf4-22v2
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-89644"]
Threat ID: 6aa4a00555bf5e2cf5a86636
Added to database: 09/12/2026, 00:42:45 UTC
Last enriched: 09/12/2026, 00:58:25 UTC
Last updated: 09/12/2026, 00:58:25 UTC
Views: 2
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