CVE-2026-98694
Description
In the Linux kernel, the following vulnerability has been resolved:
thunderbolt: Fix KASAN reported use-after-free when request is canceled
Alan reported that when doing stress testing sometimes KASAN notices
use-after-free during control channel operation (stripped down keeping
the relevant parts):
BUG: KASAN: slab-use-after-free in tb_cfg_request_sync+0x240/0x250 [thunderbolt]
Read of size 24 at addr ffff88811067f290 by task kworker/u40:2/1760
<TASK>
tb_cfg_request_sync+0x240/0x250 [thunderbolt]
tb_cfg_read_raw+0x367/0x510 [thunderbolt]
tb_cfg_read+0xec/0x240 [thunderbolt]
tb_port_get_link_generation+0x258/0x420 [thunderbolt]
tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt]
tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt]
tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt]
tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt]
tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt]
process_one_work+0x675/0x1230
worker_thread+0x5e6/0xf70
kthread+0x365/0x470
ret_from_fork+0x54d/0x710
ret_from_fork_asm+0x1a/0x30
</TASK>
Allocated by task 1760:
__kmalloc_cache_noprof+0x1ee/0x550
tb_cfg_read_raw+0x1d3/0x510 [thunderbolt]
tb_cfg_read+0xec/0x240 [thunderbolt]
tb_port_get_link_generation+0x258/0x420 [thunderbolt]
tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt]
tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt]
tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt]
tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt]
tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt]
process_one_work+0x675/0x1230
worker_thread+0x5e6/0xf70
kthread+0x365/0x470
ret_from_fork+0x54d/0x710
ret_from_fork_asm+0x1a/0x30
Freed by task 926:
kfree+0x18f/0x4a0
tb_cfg_request_put+0xb7/0xe0 [thunderbolt]
tb_cfg_request_work+0x82/0x120 [thunderbolt]
process_one_work+0x675/0x1230
worker_thread+0x5e6/0xf70
kthread+0x365/0x470
ret_from_fork+0x54d/0x710
ret_from_fork_asm+0x1a/0x30
Second to last potentially related work creation:
__queue_work+0x575/0xd00
queue_work_on+0x77/0x80
tb_cfg_request_cancel+0xc7/0x260 [thunderbolt]
tb_cfg_request_sync+0x1f6/0x250 [thunderbolt]
tb_cfg_read_raw+0x367/0x510 [thunderbolt]
tb_cfg_read+0xec/0x240 [thunderbolt]
tb_port_get_link_generation+0x258/0x420 [thunderbolt]
tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt]
tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt]
tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt]
tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt]
tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt]
process_one_work+0x675/0x1230
worker_thread+0x5e6/0xf70
kthread+0x365/0x470
ret_from_fork+0x54d/0x710
ret_from_fork_asm+0x1a/0x30
The last stack trace is helpful because it shows that we are cancelling
a request and looking at tb_cfg_request_cancel() what might happen is
that tb_cfg_request_work() completes right before tb_cfg_request_cancel()
starts and because of this it will call schedule_work() queueing the
same work to run again. However, it is already removed from the
request_queue and reference count is dropped so when
tb_cfg_request_work() triggers again it will access memory that is
already released.
Fix this so that we first make sure a cancelled request is not handed
away from tb_cfg_request_find() or scheduled to run. Then instead of
relying on the worker to clean up the request we will do it in
tb_cfg_request_cancel() after the work is canceled from running. Make
tb_cfg_request_dequeue() release the request only if it was actually
removed from the queue.
EPSS (Exploit Prediction Scoring System)
EPSS (Exploit Prediction Scoring System)
Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.