In the Linux kernel, the following vulnerability has been resolved: wifi: libertas: fix use-after-free in lbs_free_adapter() The lbs_free_adapter() function uses timer_delete() (non-synchronous) for both command_timer and tx_lockup_tim…

Overview

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

wifi: libertas: fix use-after-free in lbs_free_adapter()

The lbs_free_adapter() function uses timer_delete() (non-synchronous) for both command_timer and tx_lockup_timer before the structure is freed. This is incorrect because timer_delete() does not wait for any running timer callback to complete.

If a timer callback is executing when lbs_free_adapter() is called, the callback will access freed memory since lbs_cfg_free() frees the containing structure immediately after lbs_free_adapter() returns.

Both timer callbacks (lbs_cmd_timeout_handler and lbs_tx_lockup_handler) access priv->driver_lock, priv->cur_cmd, priv->dev, and other fields, which would all be use-after-free violations.

Use timer_delete_sync() instead to ensure any running timer callback has completed before returning.

This bug was introduced in commit 8f641d93c38a ("libertas: detect TX lockups and reset hardware") where del_timer() was used instead of del_timer_sync() in the cleanup path. The command_timer has had the same issue since the driver was first written.

Affected

• linux_kernel >= 2.6.24, < 5.10.253
• linux_kernel >= 5.11, < 5.15.203
• linux_kernel >= 5.16, < 6.1.167
• linux_kernel >= 6.2, < 6.6.130
• linux_kernel >= 6.7, < 6.12.78
• linux_kernel >= 6.13, < 6.18.17
• linux_kernel >= 6.19, < 6.19.7
• linux_kernel = 7.0

Remediation

Upgrade past the affected range:

• linux_kernel 6.19.7