fsmgr: fix integer overflow in fs_mgr am: e28dc48de5

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/11882481

Change-Id: I4af65dffeac85cb43e33929451029073b40151b1
diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index 1c5bb6c..22d1284 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -331,7 +331,7 @@
             // try backup superblock, if main superblock is corrupted
             for (unsigned int blocksize = EXT4_MIN_BLOCK_SIZE; blocksize <= EXT4_MAX_BLOCK_SIZE;
                  blocksize *= 2) {
-                unsigned int superblock = blocksize * 8;
+                uint64_t superblock = blocksize * 8;
                 if (blocksize == EXT4_MIN_BLOCK_SIZE) superblock++;
 
                 if (TEMP_FAILURE_RETRY(pread(fd, sb, sizeof(*sb), superblock * blocksize)) !=