From c4dde3d0ab12afce7bc1e90089fee6c37724752e Mon Sep 17 00:00:00 2001
From: Agniva De Sarker <agnivade@yahoo.co.in>
Date: Wed, 9 Jul 2025 09:37:36 +0530
Subject: [PATCH] MM-64632: Fix a panic in bulk import (#33360)

We were incorrect de-referencing the channels slice
without checking for nil pointer first.

https://mattermost.atlassian.net/browse/MM-64632
```release-note
NONE
```
---
 .../channels/app/imports/import_validators.go   | 17 +++++++++--------
 .../app/imports/import_validators_test.go       | 13 +++++++++++++
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/server/channels/app/imports/import_validators.go b/server/channels/app/imports/import_validators.go
index 8fa3f7ff1b..f9bbc6dd31 100644
--- a/server/channels/app/imports/import_validators.go
+++ b/server/channels/app/imports/import_validators.go
@@ -791,16 +791,17 @@ func isValidGuestRoles(data UserImportData) bool {
 				gtc++
 			}
 
-			if *team.Channels != nil {
-				for _, channel := range *team.Channels {
-					if channel.Roles != nil && model.IsInRole(*channel.Roles, model.ChannelGuestRoleId) {
-						ctc++
-					}
+			if team.Channels == nil {
+				continue
+			}
+			for _, channel := range *team.Channels {
+				if channel.Roles != nil && model.IsInRole(*channel.Roles, model.ChannelGuestRoleId) {
+					ctc++
 				}
+			}
 
-				if ctc == len(*team.Channels) {
-					isChannelGuest = true
-				}
+			if ctc == len(*team.Channels) {
+				isChannelGuest = true
 			}
 		}
 		if gtc == len(*data.Teams) {
diff --git a/server/channels/app/imports/import_validators_test.go b/server/channels/app/imports/import_validators_test.go
index 17b6647c8c..4502d2772e 100644
--- a/server/channels/app/imports/import_validators_test.go
+++ b/server/channels/app/imports/import_validators_test.go
@@ -1704,6 +1704,19 @@ func TestIsValidGuestRoles(t *testing.T) {
 			},
 			expected: true,
 		},
+		{
+			name: "Valid case: User with team but nil channels array",
+			input: UserImportData{
+				Roles: model.NewPointer(model.SystemUserRoleId),
+				Teams: &[]UserTeamImportData{
+					{
+						Roles:    model.NewPointer(model.TeamUserRoleId),
+						Channels: nil,
+					},
+				},
+			},
+			expected: true,
+		},
 	}
 
 	for _, tc := range testCases {