{"id":"AZL-50874","summary":"CVE-2024-47689 affecting package kernel for versions less than 6.6.56.1-5","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to don't set SB_RDONLY in f2fs_handle_critical_error()\n\nsyzbot reports a f2fs bug as below:\n\n------------[ cut here ]------------\nWARNING: CPU: 1 PID: 58 at kernel/rcu/sync.c:177 rcu_sync_dtor+0xcd/0x180 kernel/rcu/sync.c:177\nCPU: 1 UID: 0 PID: 58 Comm: kworker/1:2 Not tainted 6.10.0-syzkaller-12562-g1722389b0d86 #0\nWorkqueue: events destroy_super_work\nRIP: 0010:rcu_sync_dtor+0xcd/0x180 kernel/rcu/sync.c:177\nCall Trace:\n percpu_free_rwsem+0x41/0x80 kernel/locking/percpu-rwsem.c:42\n destroy_super_work+0xec/0x130 fs/super.c:282\n process_one_work kernel/workqueue.c:3231 [inline]\n process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312\n worker_thread+0x86d/0xd40 kernel/workqueue.c:3390\n kthread+0x2f0/0x390 kernel/kthread.c:389\n ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n\nAs Christian Brauner pointed out [1]: the root cause is f2fs sets\nSB_RDONLY flag in internal function, rather than setting the flag\ncovered w/ sb-\u003es_umount semaphore via remount procedure, then below\nrace condition causes this bug:\n\n- freeze_super()\n - sb_wait_write(sb, SB_FREEZE_WRITE)\n - sb_wait_write(sb, SB_FREEZE_PAGEFAULT)\n - sb_wait_write(sb, SB_FREEZE_FS)\n\t\t\t\t\t- f2fs_handle_critical_error\n\t\t\t\t\t - sb-\u003es_flags |= SB_RDONLY\n- thaw_super\n - thaw_super_locked\n  - sb_rdonly() is true, so it skips\n    sb_freeze_unlock(sb, SB_FREEZE_FS)\n  - deactivate_locked_super\n\nSince f2fs has almost the same logic as ext4 [2] when handling critical\nerror in filesystem if it mounts w/ errors=remount-ro option:\n- set CP_ERROR_FLAG flag which indicates filesystem is stopped\n- record errors to superblock\n- set SB_RDONLY falg\nOnce we set CP_ERROR_FLAG flag, all writable interfaces can detect the\nflag and stop any further updates on filesystem. So, it is safe to not\nset SB_RDONLY flag, let's remove the logic and keep in line w/ ext4 [3].\n\n[1] https://lore.kernel.org/all/20240729-himbeeren-funknetz-96e62f9c7aee@brauner\n[2] https://lore.kernel.org/all/20240729132721.hxih6ehigadqf7wx@quack3\n[3] https://lore.kernel.org/linux-ext4/20240805201241.27286-1-jack@suse.cz","modified":"2026-04-21T04:30:27.942815Z","published":"2024-10-21T12:15:05Z","upstream":["CVE-2024-47689"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-47689"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.56.1-5"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-50874.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}