Description (CNA)
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: <TASK> __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e is req->cb(req). req->cb 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
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected fd8aa9095a95c02dcc35540a263267c29b8fda9d before 0e94a246bb6d9538010b6c02d2b1d4717a97b2e5; affected fd8aa9095a95c02dcc35540a263267c29b8fda9d before f1bcac367bc95631afbb918348f30dec887d0e1b; affected fd8aa9095a95c02dcc35540a263267c29b8fda9d before 4d260a5558df4650eb87bc41b2c9ac2d6b2ba447; affected fd8aa9095a95c02dcc35540a263267c29b8fda9d before 8b02f85e84dc6f7c150cef40ddb69af5a25659e5; affected fd8aa9095a95c02dcc35540a263267c29b8fda9d before cbfaf46b88a4c01b64c4186cdccd766c19ae644c; affected fd8aa9095a95c02dcc35540a263267c29b8fda9d before 8e9c8a0393b5f85f1820c565ab8105660f4e8f92; affected fd8aa9095a95c02dcc35540a263267c29b8fda9d before 2466b0f66795c3c426cacc8998499f38031dbb59; affected fd8aa9095a95c02dcc35540a263267c29b8fda9d before 1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27 |
| Linux / Linux | affected 4.11; unaffected 0 before 4.11; unaffected 5.4.294 through 5.4.*; unaffected 5.10.238 through 5.10.*; unaffected 5.15.183 through 5.15.*; unaffected 6.1.139 through 6.1.*; unaffected 6.6.91 through 6.6.*; unaffected 6.12.29 through 6.12.*; unaffected 6.14.7 through 6.14.*; unaffected 6.15 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5
- https://git.kernel.org/stable/c/f1bcac367bc95631afbb918348f30dec887d0e1b
- https://git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447
- https://git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5
- https://git.kernel.org/stable/c/cbfaf46b88a4c01b64c4186cdccd766c19ae644c
- https://git.kernel.org/stable/c/8e9c8a0393b5f85f1820c565ab8105660f4e8f92
- https://git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59
- https://git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27
ADP enrichment
No English description supplied.
No English description supplied.
No references supplied.