Limit the maximum resolve depth to prevent infinite loops (#3896)

* Limit the maximum resolve depth to prevent infinite loops Co-authored-by: Cheng Zhou <zhoucheng@juicedata.io>
juicedata · Jul 13, 2023 · 9077586 · 9077586
1 parent 4e28868
commit 9077586
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Showing 2 changed files with 30 additions and 4 deletions.
diff --git a/.github/scripts/command/sync_minio.sh b/.github/scripts/command/sync_minio.sh
@@ -95,13 +95,32 @@ test_sync_external_link(){
     [ -z $(./mc cat myminio/myjfs/hello) ]
 }
 
-skip_test_sync_broken_link(){
+test_sync_loop_symlink(){
     prepare_test
     touch hello
     ln -s hello /jfs/hello
-    ./juicefs sync minio://minioadmin:minioadmin@localhost:9005/myjfs/ myjfs/ && exit 1 || true
+    ./juicefs sync minio://minioadmin:minioadmin@localhost:9005/myjfs/ minio://minioadmin:minioadmin@localhost:9000/myjfs/ && exit 1 || true
     rm -rf /jfs/hello
-    ./juicefs sync minio://minioadmin:minioadmin@localhost:9005/myjfs/ myjfs/
+    ./juicefs sync minio://minioadmin:minioadmin@localhost:9005/myjfs/ minio://minioadmin:minioadmin@localhost:9000/myjfs/
+}
+
+test_sync_deep_symlink(){
+    prepare_test
+    cd /jfs
+    echo hello > hello
+    ln -s hello symlink_1
+    for i in {1..40}; do
+        ln -s symlink_$i symlink_$((i+1))
+    done
+    cat symlink_40 | grep hello
+    cat symlink_41 && echo "cat symlink_41 fail" && exit 1 || true
+    cd -
+    ./juicefs sync minio://minioadmin:minioadmin@localhost:9005/myjfs/ minio://minioadmin:minioadmin@localhost:9000/myjfs/ && echo "sync should fail" && exit 1 || true
+    rm -rf /jfs/symlink_41
+    ./juicefs sync minio://minioadmin:minioadmin@localhost:9005/myjfs/ minio://minioadmin:minioadmin@localhost:9000/myjfs/ 
+    for i in {1..40}; do
+        ./mc cat myminio/myjfs/symlink_$i | grep "^hello$"
+    done
 }
 
 prepare_test(){

diff --git a/pkg/fs/fs.go b/pkg/fs/fs.go
@@ -681,6 +681,10 @@ func (fs *FileSystem) lookup(ctx meta.Context, parent Ino, name string, inode *I
 }
 
 func (fs *FileSystem) resolve(ctx meta.Context, p string, followLastSymlink bool) (fi *FileStat, err syscall.Errno) {
+	return fs.doResolve(ctx, p, followLastSymlink, 0)
+}
+
+func (fs *FileSystem) doResolve(ctx meta.Context, p string, followLastSymlink bool, depth int) (fi *FileStat, err syscall.Errno) {
 	var inode Ino
 	var attr = &Attr{}
 
@@ -736,6 +740,9 @@ func (fs *FileSystem) resolve(ctx meta.Context, p string, followLastSymlink bool
 		}
 		fi = AttrToFileInfo(inode, attr)
 		if (!resolved || followLastSymlink) && fi.IsSymlink() {
+			if depth > 39 {
+				return nil, syscall.ELOOP
+			}
 			var buf []byte
 			err = fs.m.ReadLink(ctx, inode, &buf)
 			if err != 0 {
@@ -746,7 +753,7 @@ func (fs *FileSystem) resolve(ctx meta.Context, p string, followLastSymlink bool
 				return &FileStat{name: target}, syscall.ENOTSUP
 			}
 			target = path.Join(strings.Join(ss[:i], "/"), target)
-			fi, err = fs.resolve(ctx, target, followLastSymlink)
+			fi, err = fs.doResolve(ctx, target, followLastSymlink, depth+1)
 			if err != 0 {
 				return
 			}