1 files changed, 18 insertions, 4 deletions

diff --git a/fs/jffs2/summary.c b/fs/jffs2/summary.c
index 2a77d3f93029..629af01e5ade 100644
--- a/fs/jffs2/summary.c
+++ b/fs/jffs2/summary.c
@@ -429,6 +429,7 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
 
                         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 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
                                             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 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
                                 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);