CVE-2021-47419

/// Technical description

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

net/sched: sch_taprio: properly cancel timer from taprio_destroy()

There is a comment in qdisc_create() about us not calling ops->reset()

in some cases.

err_out4:

/*

* Any broken qdiscs that would require a ops->reset() here?

* The qdisc was never in action so it shouldn't be necessary.

*/

As taprio sets a timer before actually receiving a packet, we need

to cancel it from ops->destroy, just in case ops->reset has not

been called.

syzbot reported:

ODEBUG: free active (active state 0) object type: hrtimer hint: advance_sched+0x0/0x9a0 arch/x86/include/asm/atomic64_64.h:22

WARNING: CPU: 0 PID: 8441 at lib/debugobjects.c:505 debug_print_object+0x16e/0x250 lib/debugobjects.c:505

Modules linked in:

CPU: 0 PID: 8441 Comm: syz-executor813 Not tainted 5.14.0-rc6-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

RIP: 0010:debug_print_object+0x16e/0x250 lib/debugo

/// 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