{"id":"CVE-2024-57806","summary":"btrfs: fix transaction atomicity bug when enabling simple quotas","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix transaction atomicity bug when enabling simple quotas\n\nSet squota incompat bit before committing the transaction that enables\nthe feature.\n\nWith the config CONFIG_BTRFS_ASSERT enabled, an assertion\nfailure occurs regarding the simple quota feature.\n\n  [5.596534] assertion failed: btrfs_fs_incompat(fs_info, SIMPLE_QUOTA), in fs/btrfs/qgroup.c:365\n  [5.597098] ------------[ cut here ]------------\n  [5.597371] kernel BUG at fs/btrfs/qgroup.c:365!\n  [5.597946] CPU: 1 UID: 0 PID: 268 Comm: mount Not tainted 6.13.0-rc2-00031-gf92f4749861b #146\n  [5.598450] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014\n  [5.599008] RIP: 0010:btrfs_read_qgroup_config+0x74d/0x7a0\n  [5.604303]  \u003cTASK\u003e\n  [5.605230]  ? btrfs_read_qgroup_config+0x74d/0x7a0\n  [5.605538]  ? exc_invalid_op+0x56/0x70\n  [5.605775]  ? btrfs_read_qgroup_config+0x74d/0x7a0\n  [5.606066]  ? asm_exc_invalid_op+0x1f/0x30\n  [5.606441]  ? btrfs_read_qgroup_config+0x74d/0x7a0\n  [5.606741]  ? btrfs_read_qgroup_config+0x74d/0x7a0\n  [5.607038]  ? try_to_wake_up+0x317/0x760\n  [5.607286]  open_ctree+0xd9c/0x1710\n  [5.607509]  btrfs_get_tree+0x58a/0x7e0\n  [5.608002]  vfs_get_tree+0x2e/0x100\n  [5.608224]  fc_mount+0x16/0x60\n  [5.608420]  btrfs_get_tree+0x2f8/0x7e0\n  [5.608897]  vfs_get_tree+0x2e/0x100\n  [5.609121]  path_mount+0x4c8/0xbc0\n  [5.609538]  __x64_sys_mount+0x10d/0x150\n\nThe issue can be easily reproduced using the following reproducer:\n\n  root@q:linux# cat repro.sh\n  set -e\n\n  mkfs.btrfs -q -f /dev/sdb\n  mount /dev/sdb /mnt/btrfs\n  btrfs quota enable -s /mnt/btrfs\n  umount /mnt/btrfs\n  mount /dev/sdb /mnt/btrfs\n\nThe issue is that when enabling quotas, at btrfs_quota_enable(), we set\nBTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE at fs_info-\u003eqgroup_flags and persist\nit in the quota root in the item with the key BTRFS_QGROUP_STATUS_KEY, but\nwe only set the incompat bit BTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA after we\ncommit the transaction used to enable simple quotas.\n\nThis means that if after that transaction commit we unmount the filesystem\nwithout starting and committing any other transaction, or we have a power\nfailure, the next time we mount the filesystem we will find the flag\nBTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE set in the item with the key\nBTRFS_QGROUP_STATUS_KEY but we will not find the incompat bit\nBTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA set in the superblock, triggering an\nassertion failure at:\n\n  btrfs_read_qgroup_config() -\u003e qgroup_read_enable_gen()\n\nTo fix this issue, set the BTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA flag\nimmediately after setting the BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE.\nThis ensures that both flags are flushed to disk within the same\ntransaction.","modified":"2026-04-02T12:25:18.103423Z","published":"2025-01-11T12:39:52.628Z","related":["USN-7379-2","USN-7380-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/57xxx/CVE-2024-57806.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/b87c9b9ba05ba6e8e2ee9ecd29a8c930b35648ed"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f2363e6fcc7938c5f0f6ac066fad0dd247598b51"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/57xxx/CVE-2024-57806.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-57806"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"182940f4f4dbd932776414744c8de64333957725"},{"fixed":"b87c9b9ba05ba6e8e2ee9ecd29a8c930b35648ed"},{"fixed":"f2363e6fcc7938c5f0f6ac066fad0dd247598b51"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-57806.json"}}],"schema_version":"1.7.5"}