bnxt_en: Check the lengths of encapsulated firmware responses.

Firmware messages that are forwarded from PF to VFs are encapsulated.
The size of these encapsulated messages must not exceed the maximum
defined message size.  Add appropriate checks to avoid oversize
messages.  Firmware messages may be expanded in future specs and
this will provide some guardrails to avoid data corruption.
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c

@@ -809,6 +809,9 @@ static int bnxt_hwrm_fwd_resp(struct bnxt *bp, struct bnxt_vf_info *vf,
 	struct hwrm_fwd_resp_input req = {0};
 	struct hwrm_fwd_resp_output *resp = bp->hwrm_cmd_resp_addr;
 
+	if (BNXT_FWD_RESP_SIZE_ERR(msg_size))
+		return -EINVAL;
+
 	bnxt_hwrm_cmd_hdr_init(bp, &req, HWRM_FWD_RESP, -1, -1);
 
 	/* Set the new target id */
@@ -845,6 +848,9 @@ static int bnxt_hwrm_fwd_err_resp(struct bnxt *bp, struct bnxt_vf_info *vf,
 	struct hwrm_reject_fwd_resp_input req = {0};
 	struct hwrm_reject_fwd_resp_output *resp = bp->hwrm_cmd_resp_addr;
 
+	if (BNXT_REJ_FWD_RESP_SIZE_ERR(msg_size))
+		return -EINVAL;
+
 	bnxt_hwrm_cmd_hdr_init(bp, &req, HWRM_REJECT_FWD_RESP, -1, -1);
 	/* Set the new target id */
 	req.target_id = cpu_to_le16(vf->fw_fid);
@@ -877,6 +883,9 @@ static int bnxt_hwrm_exec_fwd_resp(struct bnxt *bp, struct bnxt_vf_info *vf,
 	struct hwrm_exec_fwd_resp_input req = {0};
 	struct hwrm_exec_fwd_resp_output *resp = bp->hwrm_cmd_resp_addr;
 
+	if (BNXT_EXEC_FWD_RESP_SIZE_ERR(msg_size))
+		return -EINVAL;
+
 	bnxt_hwrm_cmd_hdr_init(bp, &req, HWRM_EXEC_FWD_RESP, -1, -1);
 	/* Set the new target id */
 	req.target_id = cpu_to_le16(vf->fw_fid);

drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.h

@@ -11,6 +11,18 @@
 #ifndef BNXT_SRIOV_H
 #define BNXT_SRIOV_H
 
+#define BNXT_FWD_RESP_SIZE_ERR(n)					\
+	((offsetof(struct hwrm_fwd_resp_input, encap_resp) + n) >	\
+	 sizeof(struct hwrm_fwd_resp_input))
+
+#define BNXT_EXEC_FWD_RESP_SIZE_ERR(n)					\
+	((offsetof(struct hwrm_exec_fwd_resp_input, encap_request) + n) >\
+	 offsetof(struct hwrm_exec_fwd_resp_input, encap_resp_target_id))
+
+#define BNXT_REJ_FWD_RESP_SIZE_ERR(n)					\
+	((offsetof(struct hwrm_reject_fwd_resp_input, encap_request) + n) >\
+	 offsetof(struct hwrm_reject_fwd_resp_input, encap_resp_target_id))
+
 int bnxt_get_vf_config(struct net_device *, int, struct ifla_vf_info *);
 int bnxt_set_vf_mac(struct net_device *, int, u8 *);
 int bnxt_set_vf_vlan(struct net_device *, int, u16, u8, __be16);