CVE-2021-47582

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

USB: core: Make do_proc_control() and do_proc_bulk() killable

The USBDEVFS_CONTROL and USBDEVFS_BULK ioctls invoke

usb_start_wait_urb(), which contains an uninterruptible wait with a

user-specified timeout value. If timeout value is very large and the

device being accessed does not respond in a reasonable amount of time,

the kernel will complain about "Task X blocked for more than N

seconds", as found in testing by syzbot:

INFO: task syz-executor.0:8700 blocked for more than 143 seconds.

Not tainted 5.14.0-rc7-syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:syz-executor.0 state:D stack:23192 pid: 8700 ppid: 8455 flags:0x00004004

Call Trace:

context_switch kernel/sched/core.c:4681 [inline]

__schedule+0xc07/0x11f0 kernel/sched/core.c:5938

schedule+0x14b/0x210 kernel/sched/core.c:6017

schedule_timeout+0x98/0x2f0 kernel/time/timer.c:1857

do_wait_for_common+0x2da/

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References