[JFFS2] Check for all-zero node headers

Due to a poor choice of CRC32 seed, a node header which is all zeroes
would pass the CRC32 check. Explicitly check for this case, and treat it
as we do a CRC failure.

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

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index 31c1475d922a..7fb45bd4915c 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -734,6 +734,15 @@ scan_more:
                         ofs += 4;
                         continue;
                 }
+                /* Due to poor choice of crc32 seed, an all-zero node will have a correct CRC */
+                if (!je32_to_cpu(node->hdr_crc) && !je16_to_cpu(node->nodetype) &&
+                    !je16_to_cpu(node->magic) && !je32_to_cpu(node->totlen)) {
+                        noisy_printk(&noise, "jffs2_scan_eraseblock(): All zero node header at 0x%08x.\n", ofs);
+                        if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
+                                return err;
+                        ofs += 4;
+                        continue;
+                }
 
                 if (ofs + je32_to_cpu(node->totlen) >
                     jeb->offset + c->sector_size) {