{"id":"CVE-2022-49079","summary":"btrfs: zoned: traverse devices under chunk_mutex in btrfs_can_activate_zone","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: zoned: traverse devices under chunk_mutex in btrfs_can_activate_zone\n\nbtrfs_can_activate_zone() can be called with the device_list_mutex already\nheld, which will lead to a deadlock:\n\ninsert_dev_extents() // Takes device_list_mutex\n`-\u003e insert_dev_extent()\n `-\u003e btrfs_insert_empty_item()\n  `-\u003e btrfs_insert_empty_items()\n   `-\u003e btrfs_search_slot()\n    `-\u003e btrfs_cow_block()\n     `-\u003e __btrfs_cow_block()\n      `-\u003e btrfs_alloc_tree_block()\n       `-\u003e btrfs_reserve_extent()\n        `-\u003e find_free_extent()\n         `-\u003e find_free_extent_update_loop()\n          `-\u003e can_allocate_chunk()\n           `-\u003e btrfs_can_activate_zone() // Takes device_list_mutex again\n\nInstead of using the RCU on fs_devices-\u003edevice_list we\ncan use fs_devices-\u003ealloc_list, protected by the chunk_mutex to traverse\nthe list of active devices.\n\nWe are in the chunk allocation thread. The newer chunk allocation\nhappens from the devices in the fs_device-\u003ealloc_list protected by the\nchunk_mutex.\n\n  btrfs_create_chunk()\n    lockdep_assert_held(&info-\u003echunk_mutex);\n    gather_device_info\n      list_for_each_entry(device, &fs_devices-\u003ealloc_list, dev_alloc_list)\n\nAlso, a device that reappears after the mount won't join the alloc_list\nyet and, it will be in the dev_list, which we don't want to consider in\nthe context of the chunk alloc.\n\n  [15.166572] WARNING: possible recursive locking detected\n  [15.167117] 5.17.0-rc6-dennis #79 Not tainted\n  [15.167487] --------------------------------------------\n  [15.167733] kworker/u8:3/146 is trying to acquire lock:\n  [15.167733] ffff888102962ee0 (&fs_devs-\u003edevice_list_mutex){+.+.}-{3:3}, at: find_free_extent+0x15a/0x14f0 [btrfs]\n  [15.167733]\n  [15.167733] but task is already holding lock:\n  [15.167733] ffff888102962ee0 (&fs_devs-\u003edevice_list_mutex){+.+.}-{3:3}, at: btrfs_create_pending_block_groups+0x20a/0x560 [btrfs]\n  [15.167733]\n  [15.167733] other info that might help us debug this:\n  [15.167733]  Possible unsafe locking scenario:\n  [15.167733]\n  [15.171834]        CPU0\n  [15.171834]        ----\n  [15.171834]   lock(&fs_devs-\u003edevice_list_mutex);\n  [15.171834]   lock(&fs_devs-\u003edevice_list_mutex);\n  [15.171834]\n  [15.171834]  *** DEADLOCK ***\n  [15.171834]\n  [15.171834]  May be due to missing lock nesting notation\n  [15.171834]\n  [15.171834] 5 locks held by kworker/u8:3/146:\n  [15.171834]  #0: ffff888100050938 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1c3/0x5a0\n  [15.171834]  #1: ffffc9000067be80 ((work_completion)(&fs_info-\u003easync_data_reclaim_work)){+.+.}-{0:0}, at: process_one_work+0x1c3/0x5a0\n  [15.176244]  #2: ffff88810521e620 (sb_internal){.+.+}-{0:0}, at: flush_space+0x335/0x600 [btrfs]\n  [15.176244]  #3: ffff888102962ee0 (&fs_devs-\u003edevice_list_mutex){+.+.}-{3:3}, at: btrfs_create_pending_block_groups+0x20a/0x560 [btrfs]\n  [15.176244]  #4: ffff8881152e4b78 (btrfs-dev-00){++++}-{3:3}, at: __btrfs_tree_lock+0x27/0x130 [btrfs]\n  [15.179641]\n  [15.179641] stack backtrace:\n  [15.179641] CPU: 1 PID: 146 Comm: kworker/u8:3 Not tainted 5.17.0-rc6-dennis #79\n  [15.179641] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1.fc35 04/01/2014\n  [15.179641] Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs]\n  [15.179641] Call Trace:\n  [15.179641]  \u003cTASK\u003e\n  [15.179641]  dump_stack_lvl+0x45/0x59\n  [15.179641]  __lock_acquire.cold+0x217/0x2b2\n  [15.179641]  lock_acquire+0xbf/0x2b0\n  [15.183838]  ? find_free_extent+0x15a/0x14f0 [btrfs]\n  [15.183838]  __mutex_lock+0x8e/0x970\n  [15.183838]  ? find_free_extent+0x15a/0x14f0 [btrfs]\n  [15.183838]  ? find_free_extent+0x15a/0x14f0 [btrfs]\n  [15.183838]  ? lock_is_held_type+0xd7/0x130\n  [15.183838]  ? find_free_extent+0x15a/0x14f0 [btrfs]\n  [15.183838]  find_free_extent+0x15a/0x14f0 [btrfs]\n  [15.183838]  ? _raw_spin_unlock+0x24/0x40\n  [15.183838]  ? btrfs_get_alloc_profile+0x106/0x230 [btrfs]\n  [15.187601]  btrfs_reserve_extent+0x131/0x260 [btrfs]\n  [15.\n---truncated---","modified":"2026-04-02T08:27:16.789808Z","published":"2025-02-26T01:54:40.697Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49079.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/09e65ae515af2b24d6dc23af21719a3b41de83e5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0b9e66762aa0cda2a9c2d5542d64e04dac528fa6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/142f822bd945a7be442a2916ec6167cc102c4183"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49079.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2022-49079"},{"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":"a85f05e59bc15a83ad910dbcb71df5ad8fa77295"},{"fixed":"09e65ae515af2b24d6dc23af21719a3b41de83e5"},{"fixed":"142f822bd945a7be442a2916ec6167cc102c4183"},{"fixed":"0b9e66762aa0cda2a9c2d5542d64e04dac528fa6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49079.json"}}],"schema_version":"1.7.5"}