From: Duoming Zhou <duoming@zju.edu.cn> stable inclusion from stable-v5.10.140 commit 50403ee6daddf0d7a14e9d3b51a377c39a08ec8c category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I63FTT Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit f1e941dbf80a9b8bab0bffbc4cbe41cc7f4c6fb6 ] 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. Fixes: c656aa4c27b1 ("nfc: pn533: add UART phy driver") Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> --- drivers/nfc/pn533/uart.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/nfc/pn533/uart.c b/drivers/nfc/pn533/uart.c index a0665d8ea85b..e92535ebb528 100644 --- a/drivers/nfc/pn533/uart.c +++ b/drivers/nfc/pn533/uart.c @@ -310,6 +310,7 @@ static void pn532_uart_remove(struct serdev_device *serdev) pn53x_unregister_nfc(pn532->priv); serdev_device_close(serdev); pn53x_common_clean(pn532->priv); + del_timer_sync(&pn532->cmd_timeout); kfree_skb(pn532->recv_skb); kfree(pn532); } -- 2.20.1