CVE-2022-50005
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.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 5.5 | 5.10.140 |
| linux / linux_kernel | 5.11 | 5.15.64 |
| linux / linux_kernel | 5.16 | 5.19.6 |
| linux / linux_kernel | 6.0-rc1 | 6.0-rc1.x |
| linux / linux_kernel | 6.0-rc2 | 6.0-rc2.x |
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