{"id":"DEBIAN-CVE-2025-37949","details":"In the Linux kernel, the following vulnerability has been resolved:  xenbus: Use kref to track req lifetime  Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace:  \u003cTASK\u003e  __wake_up_common_lock+0x82/0xd0  process_msg+0x18e/0x2f0  xenbus_thread+0x165/0x1c0  process_msg+0x18e is req-\u003ecb(req).  req-\u003ecb is set to xs_wake_up(), a thin wrapper around wake_up(), or xenbus_dev_queue_reply().  It seems like it was xs_wake_up() in this case.  It seems like req may have woken up the xs_wait_for_reply(), which kfree()ed the req.  When xenbus_thread resumes, it faults on the zero-ed data.  Linux Device Drivers 2nd edition states: \"Normally, a wake_up call can cause an immediate reschedule to happen, meaning that other processes might run before wake_up returns.\" ... which would match the behaviour observed.  Change to keeping two krefs on each request.  One for the caller, and one for xenbus_thread.  Each will kref_put() when finished, and the last will free it.  This use of kref matches the description in Documentation/core-api/kref.rst","modified":"2026-09-01T16:06:13.299578935Z","published":"2025-05-20T16:15:32.920Z","upstream":["CVE-2025-37949"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-37949"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.140-1"}]}],"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","6.1.27-1","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 yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-37949.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.29-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-37949.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.29-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-37949.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}