[JFFS2] Handle dirents on the flash with embedded zero bytes in names.

In three places: summary scan, normal scan, REF_PRISTINE GC.

Just truncate at the NUL, since that was the correct thing to do in the
only case where this (inexplicable) breakage has been seen.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

3 files changed, 35 insertions, 9 deletions

diff --git a/fs/jffs2/gc.c b/fs/jffs2/gc.c
index 95be264fe9b6..f25e485ed879 100644
--- a/fs/jffs2/gc.c
+++ b/fs/jffs2/gc.c
@@ -608,10 +608,15 @@ static int jffs2_garbage_collect_pristine(struct jffs2_sb_info *c,
                         goto bail;
                 }
 
+                if (strnlen(node->d.name, node->d.nsize) != node->d.nsize) {
+                        printk(KERN_WARNING "Name in dirent node at 0x%08x contains zeroes\n", ref_offset(raw));
+                        goto bail;
+                }
+
                 if (node->d.nsize) {
                         crc = crc32(0, node->d.name, node->d.nsize);
                         if (je32_to_cpu(node->d.name_crc) != crc) {
-                                printk(KERN_WARNING "Name CRC failed on REF_PRISTINE dirent ode at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+                                printk(KERN_WARNING "Name CRC failed on REF_PRISTINE dirent node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
                                        ref_offset(raw), je32_to_cpu(node->d.name_crc), crc);
                                 goto bail;
                         }
diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index 35ef8d83366f..272872d27fd5 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -1004,6 +1004,7 @@ static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblo
 {
         struct jffs2_full_dirent *fd;
         struct jffs2_inode_cache *ic;
+        uint32_t checkedlen;
         uint32_t crc;
         int err;
 
@@ -1024,12 +1025,18 @@ static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblo
 
         pseudo_random += je32_to_cpu(rd->version);
 
-        fd = jffs2_alloc_full_dirent(rd->nsize+1);
+        /* Should never happen. Did. (OLPC trac #4184)*/
+        checkedlen = strnlen(rd->name, rd->nsize);
+        if (checkedlen < rd->nsize) {
+                printk(KERN_ERR "Dirent at %08x has zeroes in name. Truncating to %d chars\n",
+                       ofs, checkedlen);
+        }
+        fd = jffs2_alloc_full_dirent(checkedlen+1);
         if (!fd) {
                 return -ENOMEM;
         }
-        memcpy(&fd->name, rd->name, rd->nsize);
-        fd->name[rd->nsize] = 0;
+        memcpy(&fd->name, rd->name, checkedlen);
+        fd->name[checkedlen] = 0;
 
         crc = crc32(0, fd->name, rd->nsize);
         if (crc != je32_to_cpu(rd->name_crc)) {
@@ -1055,7 +1062,7 @@ static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblo
         fd->next = NULL;
         fd->version = je32_to_cpu(rd->version);
         fd->ino = je32_to_cpu(rd->ino);
-        fd->nhash = full_name_hash(fd->name, rd->nsize);
+        fd->nhash = full_name_hash(fd->name, checkedlen);
         fd->type = rd->type;
         jffs2_add_fd_to_list(c, fd, &ic->scan_dents);
 
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);