CVE-2024-50145: NULL Pointer Dereference

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

octeon_ep: Add SKB allocation failures handling in __octep_oq_process_rx()

build_skb() returns NULL in case of a memory allocation failure so handle it inside __octep_oq_process_rx() to avoid NULL pointer dereference.

__octep_oq_process_rx() is called during NAPI polling by the driver. If skb allocation fails, keep on pulling packets out of the Rx DMA queue: we shouldn't break the polling immediately and thus falsely indicate to the octep_napi_poll() that the Rx pressure is going down. As there is no associated skb in this case, don't process the packets and don't push them up the network stack - they are skipped.

Helper function is implemented to unmmap/flush all the fragment buffers used by the dropped packet. 'alloc_failures' counter is incremented to mark the skb allocation error in driver statistics.

Found by Linux Verification Center (linuxtesting.org) with SVACE.