CVE-2024-57806: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-57806 is a transaction atomicity bug in the Linux kernel's BTRFS filesystem that affects the simple quota feature. The vulnerability was discovered and disclosed on January 11, 2025. The issue occurs when enabling simple quotas in BTRFS, where the incompat bit BTRFSFEATUREINCOMPATSIMPLEQUOTA is set after committing the transaction that enables the feature, leading to potential inconsistencies (Kernel Git).

The vulnerability manifests when enabling quotas in BTRFS, specifically during the btrfsquotaenable() function execution. The bug occurs because BTRFSQGROUPSTATUSFLAGSIMPLEMODE is set at fsinfo->qgroupflags and persisted in the quota root with the BTRFSQGROUPSTATUSKEY, but the incompat bit BTRFSFEATUREINCOMPATSIMPLEQUOTA is only set after committing the transaction. With CONFIGBTRFSASSERT enabled, this triggers an assertion failure at btrfsreadqgroupconfig() -> qgroupreadenablegen() (NVD).

If the filesystem is unmounted without starting and committing any other transaction after the initial quota enabling transaction, or if a power failure occurs, the next mount operation will find inconsistent states between the BTRFSQGROUPSTATUSFLAGSIMPLEMODE flag and the BTRFSFEATUREINCOMPATSIMPLE_QUOTA bit, leading to an assertion failure (Kernel Git).

The fix involves setting the BTRFSFEATUREINCOMPATSIMPLEQUOTA flag immediately after setting the BTRFSQGROUPSTATUSFLAGSIMPLE_MODE, ensuring both flags are flushed to disk within the same transaction. This patch has been merged into the Linux kernel (Kernel Git).