[PATCH iwl-net] ice: fix bound parser hash offset before reading packet data

ice_rt_ho_set() uses the HO register as the starting offset of an
ICE_GPR_HV_SIZE-byte memcpy() out of rt->pkt_buf. Potentially HO can
be advanced by user-controlled data reachable through
ice_parse_raw_rss_pattern() -> ice_parser_run() ->
ice_parser_rt_execute() -> ice_rt_gpr_set() -> ice_rt_ho_set(), i.e. a
VF-supplied raw RSS pattern (virt/rss.c), with no bound against the
size of pkt_buf.

Clamp HO to the last offset from which ICE_GPR_HV_SIZE bytes can still
be read out of pkt_buf, deriving the limit from sizeof(rt->pkt_buf)
so it stays correct if the packet buffer layout changes.

Fixes: 9a4c07aaa0f5 ("ice: add parser execution main loop")
Cc: [email protected]
Signed-off-by: Aleksandr Loktionov <[email protected]>
Reviewed-by: Przemek Kitszel <[email protected]>
---
 drivers/net/ethernet/intel/ice/ice_parser_rt.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/intel/ice/ice_parser_rt.c b/drivers/net/ethernet/intel/ice/ice_parser_rt.c
index 3995d66..bfdb50b 100644
--- a/drivers/net/ethernet/intel/ice/ice_parser_rt.c
+++ b/drivers/net/ethernet/intel/ice/ice_parser_rt.c
@@ -10,6 +10,8 @@ static void ice_rt_tsr_set(struct ice_parser_rt *rt, u16 tsr)
 
 static void ice_rt_ho_set(struct ice_parser_rt *rt, u16 ho)
 {
+	/* keep the ICE_GPR_HV_SIZE-byte read below within pkt_buf */
+	ho = min_t(u16, ho, sizeof(rt->pkt_buf) - ICE_GPR_HV_SIZE);
 	rt->gpr[ICE_GPR_HO_IDX] = ho;
 	memcpy(&rt->gpr[ICE_GPR_HV_IDX], &rt->pkt_buf[ho], ICE_GPR_HV_SIZE);
 }
-- 
2.52.0