From 9165b7dbeb85ef50109ae6e3671dbbbcab224867 Mon Sep 17 00:00:00 2001
From: Florian Schade <f.schade@icloud.com>
Date: Wed, 16 Oct 2024 09:40:22 +0200
Subject: [PATCH] fix: shareCache concurrency panic

---
 .../fix-sharecache-concurrency-panic.md       |  5 +++++
 .../usershareprovider/usershareprovider.go    | 19 ++++++++++++-------
 .../manager/jsoncs3/sharecache/sharecache.go  |  8 +++++---
 3 files changed, 22 insertions(+), 10 deletions(-)
 create mode 100644 changelog/unreleased/fix-sharecache-concurrency-panic.md

diff --git a/changelog/unreleased/fix-sharecache-concurrency-panic.md b/changelog/unreleased/fix-sharecache-concurrency-panic.md
new file mode 100644
index 0000000000..168dfe8dc8
--- /dev/null
+++ b/changelog/unreleased/fix-sharecache-concurrency-panic.md
@@ -0,0 +1,5 @@
+Bugfix: Fix ShareCache concurrency panic
+
+We fixed an issue where concurrently read and write operations led to a panic in the ShareCache. 
+
+https://github.com/cs3org/reva/pull/4887
diff --git a/internal/grpc/services/usershareprovider/usershareprovider.go b/internal/grpc/services/usershareprovider/usershareprovider.go
index 60433148df..3d2247a42e 100644
--- a/internal/grpc/services/usershareprovider/usershareprovider.go
+++ b/internal/grpc/services/usershareprovider/usershareprovider.go
@@ -535,16 +535,21 @@ func (s *service) UpdateReceivedShare(ctx context.Context, req *collaboration.Up
 	var uid userpb.UserId
 	_ = utils.ReadJSONFromOpaque(req.Opaque, "userid", &uid)
 	updatedShare, err := s.sm.UpdateReceivedShare(ctx, req.Share, req.UpdateMask, &uid)
-	if err != nil {
+	switch err.(type) {
+	case nil:
+		return &collaboration.UpdateReceivedShareResponse{
+			Status: status.NewOK(ctx),
+			Share:  updatedShare,
+		}, nil
+	case errtypes.NotFound:
 		return &collaboration.UpdateReceivedShareResponse{
-			Status: status.NewInternal(ctx, "error updating received share"),
+			Status: status.NewNotFound(ctx, "error getting received share"),
+		}, nil
+	default:
+		return &collaboration.UpdateReceivedShareResponse{
+			Status: status.NewInternal(ctx, "error getting received share"),
 		}, nil
 	}
-
-	return &collaboration.UpdateReceivedShareResponse{
-		Status: status.NewOK(ctx),
-		Share:  updatedShare,
-	}, nil
 }
 
 func setReceivedShareMountPoint(ctx context.Context, gwc gateway.GatewayAPIClient, req *collaboration.UpdateReceivedShareRequest) (*rpc.Status, error) {
diff --git a/pkg/share/manager/jsoncs3/sharecache/sharecache.go b/pkg/share/manager/jsoncs3/sharecache/sharecache.go
index 3d6fbe7037..f763dee0f8 100644
--- a/pkg/share/manager/jsoncs3/sharecache/sharecache.go
+++ b/pkg/share/manager/jsoncs3/sharecache/sharecache.go
@@ -28,13 +28,15 @@ import (
 	"sync"
 	"time"
 
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"golang.org/x/exp/maps"
+
 	"github.com/cs3org/reva/v2/pkg/appctx"
 	"github.com/cs3org/reva/v2/pkg/errtypes"
 	"github.com/cs3org/reva/v2/pkg/share/manager/jsoncs3/shareid"
 	"github.com/cs3org/reva/v2/pkg/storage/utils/decomposedfs/mtimesyncedcache"
 	"github.com/cs3org/reva/v2/pkg/storage/utils/metadata"
-	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/codes"
 )
 
 // name is the Tracer name used to identify this instrumentation library.
@@ -246,7 +248,7 @@ func (c *Cache) List(ctx context.Context, userid string) (map[string]SpaceShareI
 
 	for ssid, cached := range us.UserShares {
 		r[ssid] = SpaceShareIDs{
-			IDs: cached.IDs,
+			IDs: maps.Clone(cached.IDs),
 		}
 	}
 	return r, nil