CVE-2023-54036

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

wifi: rtl8xxxu: Fix memory leaks with RTL8723BU, RTL8192EU

The wifi + bluetooth combo chip RTL8723BU can leak memory (especially?) when it's connected to a bluetooth audio device. The busy bluetooth traffic generates lots of C2H (card to host) messages, which are not freed correctly.

To fix this, move the devkfreeskb() call in rtl8xxxuc2hcmdcallback() inside the loop where skb_dequeue() is called.

The RTL8192EU leaks memory because the C2H messages are added to the queue and left there forever. (This was fine in the past because it probably wasn't sending any C2H messages until commit e542e66b7c2e ("wifi: rtl8xxxu: gen2: Turn on the rate control"). Since that commit it sends a C2H message when the TX rate changes.)

To fix this, delete the check for rf_paths > 1 and the goto. Let the function process the C2H messages from RTL8192EU like the ones from the other chips.

Theoretically the RTL8188FU could also leak like RTL8723BU, but it most likely doesn't send C2H messages frequently enough.

This change was tested with RTL8723BU by Erhard F. I tested it with RTL8188FU and RTL8192EU.