{"id":"DEBIAN-CVE-2025-68807","details":"In the Linux kernel, the following vulnerability has been resolved:  block: fix race between wbt_enable_default and IO submission  When wbt_enable_default() is moved out of queue freezing in elevator_change(), it can cause the wbt inflight counter to become negative (-1), leading to hung tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter is in an inconsistent state.  The issue occurs because wbt_enable_default() could race with IO submission, allowing the counter to be decremented before proper initialization. This manifests as:    rq_wait[0]:     inflight:             -1     has_waiters:        True  rwb_enabled() checks the state, which can be updated exactly between wbt_wait() (rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter will become negative.  And results in hung task warnings like:   task:kworker/u24:39 state:D stack:0 pid:14767   Call Trace:     rq_qos_wait+0xb4/0x150     wbt_wait+0xa9/0x100     __rq_qos_throttle+0x24/0x40     blk_mq_submit_bio+0x672/0x7b0     ...  Fix this by:  1. Splitting wbt_enable_default() into:    - __wbt_enable_default(): Returns true if wbt_init() should be called    - wbt_enable_default(): Wrapper for existing callers (no init)    - wbt_init_enable_default(): New function that checks and inits WBT  2. Using wbt_init_enable_default() in blk_register_queue() to ensure    proper initialization during queue registration  3. Move wbt_init() out of wbt_enable_default() which is only for enabling    disabled wbt from bfq and iocost, and wbt_init() isn't needed. Then the    original lock warning can be avoided.  4. Removing the ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT flag and its handling    code since it's no longer needed  This ensures WBT is properly initialized before any IO can be submitted, preventing the counter from going negative.","modified":"2026-08-27T22:49:03.065649985Z","published":"2026-01-13T16:16:02.857Z","upstream":["CVE-2025-68807"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-68807"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.18.3-1"}]}],"versions":["6.12.100-1","6.12.101-1","6.12.105-1","6.12.38-1","6.12.41-1","6.12.43-1","6.12.43-1~bpo12+1","6.12.48-1","6.12.57-1","6.12.57-1~bpo12+1","6.12.63-1","6.12.63-1~bpo12+1","6.12.69-1","6.12.69-1~bpo12+1","6.12.73-1","6.12.73-1~bpo12+1","6.12.74-1","6.12.74-2","6.12.74-2~bpo12+1","6.12.85-1","6.12.85-1~bpo12+1","6.12.86-1","6.12.86-1~bpo12+1","6.12.88-1","6.12.88-1~bpo12+1","6.12.90-1","6.12.90-1~bpo12+1","6.12.90-2","6.12.90-2~bpo12+1","6.12.94-1","6.12.94-1~bpo12+1","6.12.95-1","6.12.95-1~bpo12+1","6.12.96-1","6.13.10-1~exp1","6.13.11-1~exp1","6.13.2-1~exp1","6.13.3-1~exp1","6.13.4-1~exp1","6.13.5-1~exp1","6.13.6-1~exp1","6.13.7-1~exp1","6.13.8-1~exp1","6.13.9-1~exp1","6.13~rc6-1~exp1","6.13~rc7-1~exp1","6.14.3-1~exp1","6.14.5-1~exp1","6.14.6-1~exp1","6.15-1~exp1","6.15.1-1~exp1","6.15.2-1~exp1","6.15.3-1~exp1","6.15.4-1~exp1","6.15.5-1~exp1","6.15.6-1~exp1","6.15~rc7-1~exp1","6.16-1~exp1","6.16.1-1~exp1","6.16.10-1","6.16.11-1","6.16.12-1","6.16.12-1~bpo13+1","6.16.12-2","6.16.3-1","6.16.3-1~bpo13+1","6.16.5-1","6.16.6-1","6.16.7-1","6.16.8-1","6.16.9-1","6.16~rc7-1~exp1","6.17.10-1","6.17.11-1","6.17.12-1","6.17.13-1","6.17.13-1~bpo13+1","6.17.2-1~exp1","6.17.5-1~exp1","6.17.6-1","6.17.7-1","6.17.7-2","6.17.8-1","6.17.8-1~bpo13+1","6.17.9-1","6.18.1-1~exp1","6.18.2-1~exp1","6.18~rc4-1~exp1","6.18~rc4-1~exp2","6.18~rc5-1~exp1","6.18~rc6-1~exp1","6.18~rc7-1~exp1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-68807.json"}}],"schema_version":"1.9.0"}