diff --git a/fs/jffs2/summary.c b/fs/jffs2/summary.c
index 2a77d3f..629af01 100644
--- a/fs/jffs2/summary.c
+++ b/fs/jffs2/summary.c
@@ -429,6 +429,7 @@
 
 			case JFFS2_NODETYPE_DIRENT: {
 				struct jffs2_sum_dirent_flash *spd;
+				int checkedlen;
 				spd = sp;
 
 				dbg_summary("Dirent at 0x%08x-0x%08x\n",
@@ -436,12 +437,25 @@
 					    jeb->offset + je32_to_cpu(spd->offset) + je32_to_cpu(spd->totlen));
 
 
-				fd = jffs2_alloc_full_dirent(spd->nsize+1);
+				/* This should never happen, but https://dev.laptop.org/ticket/4184 */
+				checkedlen = strnlen(spd->name, spd->nsize);
+				if (!checkedlen) {
+					printk(KERN_ERR "Dirent at %08x has zero at start of name. Aborting mount.\n",
+					       jeb->offset + je32_to_cpu(spd->offset));
+					return -EIO;
+				}
+				if (checkedlen < spd->nsize) {
+					printk(KERN_ERR "Dirent at %08x has zeroes in name. Truncating to %d chars\n",
+					       jeb->offset + je32_to_cpu(spd->offset), checkedlen);
+				}
+
+
+				fd = jffs2_alloc_full_dirent(checkedlen+1);
 				if (!fd)
 					return -ENOMEM;
 
-				memcpy(&fd->name, spd->name, spd->nsize);
-				fd->name[spd->nsize] = 0;
+				memcpy(&fd->name, spd->name, checkedlen);
+				fd->name[checkedlen] = 0;
 
 				ic = jffs2_scan_make_ino_cache(c, je32_to_cpu(spd->pino));
 				if (!ic) {
@@ -455,7 +469,7 @@
 				fd->next = NULL;
 				fd->version = je32_to_cpu(spd->version);
 				fd->ino = je32_to_cpu(spd->ino);
-				fd->nhash = full_name_hash(fd->name, spd->nsize);
+				fd->nhash = full_name_hash(fd->name, checkedlen);
 				fd->type = spd->type;
 
 				jffs2_add_fd_to_list(c, fd, &ic->scan_dents);