From 3183d0b68072dda0e80bb6e03c970625f2823e97 Mon Sep 17 00:00:00 2001
From: Andrew Gallatin <gallatin@FreeBSD.org>
Date: Fri, 23 Apr 2021 05:51:22 -0400
Subject: [PATCH] iflib: initialize LRO unconditionally

Changes to the LRO code have exposed a bug in iflib where devices
which are not capable of doing LRO are still calling
tcp_lro_flush_all(), even when they have not initialized the LRO
context. This used to be mostly harmless, but the LRO code now sets
the VNET based on the ifp in the lro context and will try to access it
through a NULL ifp resulting in a panic at boot.

To fix this, we unconditionally initializes LRO so that we have a
valid LRO context when calling tcp_lro_flush_all(). One alternative is
to check the device capabilities before calling tcp_lro_flush_all() or
adding a new state flag in the ctx. However, it seems unwise to add an
extra, mostly useless test for higher performance devices when we can
just initialize LRO for all devices.

Reviewed by: erj, hselasky, markj, olivier
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D29928
---
 sys/net/iflib.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/sys/net/iflib.c b/sys/net/iflib.c
index 6dbaff556a15..fc0814d0fc19 100644
--- a/sys/net/iflib.c
+++ b/sys/net/iflib.c
@@ -5891,15 +5891,13 @@ iflib_rx_structures_setup(if_ctx_t ctx)
 
 	for (q = 0; q < ctx->ifc_softc_ctx.isc_nrxqsets; q++, rxq++) {
 #if defined(INET6) || defined(INET)
-		if (if_getcapabilities(ctx->ifc_ifp) & IFCAP_LRO) {
-			err = tcp_lro_init_args(&rxq->ifr_lc, ctx->ifc_ifp,
-			    TCP_LRO_ENTRIES, min(1024,
-			    ctx->ifc_softc_ctx.isc_nrxd[rxq->ifr_fl_offset]));
-			if (err != 0) {
-				device_printf(ctx->ifc_dev,
-				    "LRO Initialization failed!\n");
-				goto fail;
-			}
+		err = tcp_lro_init_args(&rxq->ifr_lc, ctx->ifc_ifp,
+		    TCP_LRO_ENTRIES, min(1024,
+		    ctx->ifc_softc_ctx.isc_nrxd[rxq->ifr_fl_offset]));
+		if (err != 0) {
+			device_printf(ctx->ifc_dev,
+			    "LRO Initialization failed!\n");
+			goto fail;
 		}
 #endif
 		IFDI_RXQ_SETUP(ctx, rxq->ifr_id);
@@ -5914,8 +5912,7 @@ iflib_rx_structures_setup(if_ctx_t ctx)
 	 */
 	rxq = ctx->ifc_rxqs;
 	for (i = 0; i < q; ++i, rxq++) {
-		if (if_getcapabilities(ctx->ifc_ifp) & IFCAP_LRO)
-			tcp_lro_free(&rxq->ifr_lc);
+		tcp_lro_free(&rxq->ifr_lc);
 	}
 	return (err);
 #endif
@@ -5938,8 +5935,7 @@ iflib_rx_structures_free(if_ctx_t ctx)
 			iflib_dma_free(&rxq->ifr_ifdi[j]);
 		iflib_rx_sds_free(rxq);
 #if defined(INET6) || defined(INET)
-		if (if_getcapabilities(ctx->ifc_ifp) & IFCAP_LRO)
-			tcp_lro_free(&rxq->ifr_lc);
+		tcp_lro_free(&rxq->ifr_lc);
 #endif
 	}
 	free(ctx->ifc_rxqs, M_IFLIB);