CVE-2021-47449

/// Technical description

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

ice: fix locking for Tx timestamp tracking flush

Commit 4dd0d5c33c3e ("ice: add lock around Tx timestamp tracker flush")

added a lock around the Tx timestamp tracker flow which is used to

cleanup any left over SKBs and prepare for device removal.

This lock is problematic because it is being held around a call to

ice_clear_phy_tstamp. The clear function takes a mutex to send a PHY

write command to firmware. This could lead to a deadlock if the mutex

actually sleeps, and causes the following warning on a kernel with

preemption debugging enabled:

[ 715.419426] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:573

[ 715.427900] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 3100, name: rmmod

[ 715.435652] INFO: lockdep is turned off.

[ 715.439591] Preemption disabled at:

[ 715.439594] [<0000000000000000>] 0x0

[ 715.446678] CPU: 52 PID: 3100 Comm: rmmod Tainted: G W OE

/// 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