{"id":"DEBIAN-CVE-2026-68132","details":"In the Linux kernel, the following vulnerability has been resolved:  super: fix emergency thaw deadlock on frozen block devices  do_thaw_all_callback() calls bdev_thaw() while holding sb-\u003es_umount exclusively. If the block device was frozen via bdev_freeze() dropping the last block layer freeze reference calls fs_bdev_thaw() which reacquires s_umount:    do_thaw_all_callback(sb)     super_lock_excl(sb)                     # holds sb-\u003es_umount     bdev_thaw(sb-\u003es_bdev)       mutex_lock(&bdev-\u003ebd_fsfreeze_mutex)       # bd_fsfreeze_count drops 1 -\u003e 0       bd_holder_ops-\u003ethaw == fs_bdev_thaw         get_bdev_super(bdev)           bdev_super_lock(bdev, true)             super_lock(sb, true)               down_write(&sb-\u003es_umount)     # same task: deadlock  The emergency thaw worker deadlocks against itself holding both s_umount and bd_fsfreeze_mutex. That fscks any subsequent unmount, freeze, or thaw of that filesystem and block device.    [   81.878470] sysrq: Show Blocked State   [   81.880140] task:kworker/0:1     state:D stack:0     pid:11    tgid:11    ppid:2      task_flags:0x4208060 flags:0x00080000   [   81.884876] Workqueue: events do_thaw_all   [   81.886656] Call Trace:   [   81.887759]  \u003cTASK\u003e   [   81.888763]  __schedule+0x579/0x1420   [   81.890372]  schedule+0x3a/0x100   [   81.891794]  schedule_preempt_disabled+0x15/0x30   [   81.893848]  rwsem_down_write_slowpath+0x1ea/0x900   [   81.895191]  ? __pfx_do_thaw_all_callback+0x10/0x10   [   81.896528]  down_write+0xbd/0xc0   [   81.897505]  super_lock+0x91/0x180   [   81.898457]  ? __mutex_lock+0xa99/0x1140   [   81.900748]  ? __mutex_unlock_slowpath+0x1f/0x400   [   81.902069]  bdev_super_lock+0x5b/0x150   [   81.903132]  get_bdev_super+0x10/0x60   [   81.904042]  fs_bdev_thaw+0x23/0xf0   [   81.904755]  bdev_thaw+0x82/0x100   [   81.905484]  do_thaw_all_callback+0x2c/0x50   [   81.906298]  __iterate_supers+0x5d/0x130   [   81.907067]  do_thaw_all+0x20/0x40   [   81.907739]  process_one_work+0x206/0x5e0   [   81.908545]  worker_thread+0x1e2/0x3c0   [   81.909339]  ? __pfx_worker_thread+0x10/0x10   [   81.910171]  kthread+0xf4/0x130   [   81.910799]  ? __pfx_kthread+0x10/0x10   [   81.911528]  ret_from_fork+0x2e2/0x3b0   [   81.912259]  ? __pfx_kthread+0x10/0x10   [   81.913010]  ret_from_fork_asm+0x1a/0x30   [   81.913806]  \u003c/TASK\u003e  bdev_super_lock() even documents the violated requirement with lockdep_assert_not_held(&sb-\u003es_umount).  Acquiring bd_fsfreeze_mutex under s_umount also inverts the bd_fsfreeze_mutex vs. s_umount ordering established by bdev_{freeze,thaw}() and can thus ABBA against a concurrent block-layer freeze even when the recursive path isn't hit.  Fix this by not holding s_umount around the bdev_thaw() loop at all. Pin the superblock with an active reference instead as filesystems_freeze_callback() does. The active reference keeps the superblock from being shut down and so -\u003es_bdev stays valid without holding s_umount. The block-layer-held freeze is dropped by fs_bdev_thaw() with FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE exactly as a regular unfreeze would and thaw_super_locked() handles filesystem-level freezes as before.  The emergency thaw path has deadlocked like this in one form or another for a long long time but the current exclusively-held shape dates back to commit [1] where thaw_bdev() already ended in thaw_super() with s_umount held by do_thaw_all_callback().","modified":"2026-09-19T22:02:16.492323610Z","published":"2026-08-10T13:19:58.607Z","upstream":["CVE-2026-68132"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-68132"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.187-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.170-1","6.1.170-2","6.1.170-3","6.1.172-1","6.1.174-1","6.1.176-1","6.1.177-1","6.1.180-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not 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