From 36c50cd1b6b7d31c6a1903b9f09983053876326c Mon Sep 17 00:00:00 2001
From: Tuetuopay <tuetuopay@me.com>
Date: Tue, 23 Apr 2024 11:03:49 +0200
Subject: [PATCH] server: fix nil pointer exception in evpn mac mobility

With large EVPN fabrics, it can happen that some paths are nil in the
mac mobility codepath, causing crashes of the process.

    panic: runtime error: invalid memory address or nil pointer dereference
    [signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0xb8e03a]
    goroutine 25 [running]:
    github.com/osrg/gobgp/v3/internal/pkg/table.(*Path).root(...)
        /home/tuetuopay/dev/gobgp/internal/pkg/table/path.go:341
    github.com/osrg/gobgp/v3/internal/pkg/table.(*Path).OriginInfo(...)
        /home/tuetuopay/dev/gobgp/internal/pkg/table/path.go:348
    github.com/osrg/gobgp/v3/internal/pkg/table.(*Path).GetNlri(...)
        /home/tuetuopay/dev/gobgp/internal/pkg/table/path.go:460
    github.com/osrg/gobgp/v3/pkg/server.getMacMobilityExtendedCommunity(0x0, {0xc002833520, 0x6, 0xc00033ec00?}, {0xc001a52008, 0xa72, 0xc000000000?})
        /home/tuetuopay/dev/gobgp/pkg/server/server.go:2044 +0x1da
    github.com/osrg/gobgp/v3/pkg/server.(*BgpServer).fixupApiPath(0xc000372008, {0x0, 0x0}, {0xc0008fbe48, 0x1, 0x0?})
        /home/tuetuopay/dev/gobgp/pkg/server/server.go:2120 +0x4bc
    github.com/osrg/gobgp/v3/pkg/server.(*BgpServer).addPathList(0xc000372008, {0x0?, 0x0?}, {0xc0008fbe48, 0x1, 0x1})
        /home/tuetuopay/dev/gobgp/pkg/server/server.go:2162 +0x2c
    github.com/osrg/gobgp/v3/pkg/server.(*BgpServer).AddPath.func1()
        /home/tuetuopay/dev/gobgp/pkg/server/server.go:2191 +0xa5
    github.com/osrg/gobgp/v3/pkg/server.(*BgpServer).handleMGMTOp(0xc0b4e0?, 0xc001243140)
        /home/tuetuopay/dev/gobgp/pkg/server/server.go:280 +0x82
    github.com/osrg/gobgp/v3/pkg/server.(*BgpServer).Serve(0xc000372008)
        /home/tuetuopay/dev/gobgp/pkg/server/server.go:490 +0x53a
    created by main.main in goroutine 1
        /home/tuetuopay/dev/gobgp/cmd/gobgpd/main.go:202 +0x13ea
---
 pkg/server/server.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pkg/server/server.go b/pkg/server/server.go
index 78f18ad5b..6207e8a8d 100644
--- a/pkg/server/server.go
+++ b/pkg/server/server.go
@@ -2041,6 +2041,9 @@ func getMacMobilityExtendedCommunity(etag uint32, mac net.HardwareAddr, evpnPath
 	}, 0)
 
 	for _, path := range evpnPaths {
+		if path == nil {
+			continue
+		}
 		nlri := path.GetNlri().(*bgp.EVPNNLRI)
 		target, ok := nlri.RouteTypeData.(*bgp.EVPNMacIPAdvertisementRoute)
 		if !ok {