Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
nfc: pn533: Fix use-after-free bugs caused by pn532_cmd_timeout
When the pn532 uart device is detaching, the pn532_uart_remove() is called. But there are no functions in pn532_uart_remove() that could delete the cmd_timeout timer, which will cause use-after-free bugs. The process is shown below:
(thread 1) | (thread 2) | pn532_uart_send_frame pn532_uart_remove | mod_timer(&pn532->cmd_timeout,…) … | (wait a time) kfree(pn532) //FREE | pn532_cmd_timeout | pn532_uart_send_frame | pn532->… //USE
This patch adds del_timer_sync() in pn532_uart_remove() in order to prevent the use-after-free bugs. What’s more, the pn53x_unregister_nfc() is well synchronized, it sets nfc_dev->shutting_down to true and there are no syscalls could restart the cmd_timeout timer.
Details
- Affected product:
- AlmaLinux 9.2 ESU , TuxCare 9.6 ESU
- Affected packages:
- kernel @ 5.14.0 (+1 more)
In the Linux kernel, the following vulnerability has been resolved:
nfc: pn533: Fix use-after-free bugs caused by pn532_cmd_timeout
When the pn532 uart device is detaching, the pn532_uart_remove() is called. But there are no functions in pn532_uart_remove() that could delete the cmd_timeout timer, which will cause use-after-free bugs. The process is shown below:
(thread 1) | (thread 2) | pn532_uart_send_frame pn532_uart_remove | mod_timer(&pn532->cmd_timeout,…) … | (wait a time) kfree(pn532) //FREE | pn532_cmd_timeout | pn532_uart_send_frame | pn532->… //USE
This patch adds del_timer_sync() in pn532_uart_remove() in order to prevent the use-after-free bugs. What’s more, the pn53x_unregister_nfc() is well synchronized, it sets nfc_dev->shutting_down to true and there are no syscalls could restart the cmd_timeout timer.