Hello,
Our static analysis tool finds some possible data races in the IMX
firmware in Linux 6.4.0.
In the function imx_scu_call_rpc(), the variable sc_ipc->msg is
accessed with holding the lock sc_ipc->lock:
imx_scu_call_rpc() --> Line 203
mutex_lock(&sc_ipc->lock); --> Line 212 (Lock sc_ipc->lock)
sc_ipc->msg = msg; --> Line 216 (Access sc_ipc->msg)
sc_ipc->msg = NULL; --> Line 251 (Access sc_ipc->msg)
However, in the function imx_scu_rx_callback(), the variable
sc_ipc->msg is accessed without holding the lock sc_ipc->lock:
imx_scu_rx_callback() --> Line 112
sc_ipc->msg[0] = *data++; --> Line 129 (Access sc_ipc->msg)
sc_ipc->msg[sc_chan->idx] = *data; --> Line 148 (Access sc_ipc->msg)
I am not sure whether the functions imx_scu_call_rpc() and
imx_scu_rx_callback() can be executed concurrently and whether
the variables sc_ipc in the two functions can be the same. If so,
harmful data races can occur because:
1. If the variable sc_ipc->msg is set to NULL after the if check at
Line 120, null-pointer dereferences may occur at Lines 129 and 148;
2. If sc_ipc->msg is changed by imx_scu_call_rpc() when updating
sc_ipc->msg with data. The values in data can be written to different
msgs and cause data-inconsistency.
I am not quite sure whether these possible data races are real and
how to fix them if they are real.
Any feedback would be appreciated, thanks!
Reported-by: BassCheck <[email protected]>
Best wishes,
Tuo Li