ice: fix crash at allocation failure

ice: fix crash at allocation failure

Fix a crash in the zero-copy driver that occurs when it fails to
allocate buffers from user-space. This crash can easily be triggered
by a malicious program that does not provide any buffers in the fill
ring for the kernel to use.

Note that this bug does not exist in upstream since the batched buffer
allocation interface got introduced in 5.16 and replaced this code.

Reported-by: Jeff Shaw <jeffrey.b.shaw@intel.com>
Tested-by: Jeff Shaw <jeffrey.b.shaw@intel.com>
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>