[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>
diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index 58a0b91..717a48c 100644
--- a/fs/jffs2/readinode.c
+++ b/fs/jffs2/readinode.c
@@ -373,7 +373,14 @@
static inline int read_unknown(struct jffs2_sb_info *c, struct jffs2_raw_node_ref *ref, struct jffs2_unknown_node *un)
{
/* We don't mark unknown nodes as REF_UNCHECKED */
- BUG_ON(ref_flags(ref) == REF_UNCHECKED);
+ if (ref_flags(ref) == REF_UNCHECKED) {
+ JFFS2_ERROR("REF_UNCHECKED but unknown node at %#08x\n",
+ ref_offset(ref));
+ JFFS2_ERROR("Node is {%04x,%04x,%08x,%08x}. Please report this error.\n",
+ je16_to_cpu(un->magic), je16_to_cpu(un->nodetype),
+ je32_to_cpu(un->totlen), je32_to_cpu(un->hdr_crc));
+ return 1;
+ }
un->nodetype = cpu_to_je16(JFFS2_NODE_ACCURATE | je16_to_cpu(un->nodetype));
@@ -576,6 +583,13 @@
jffs2_mark_node_obsolete(c, ref);
goto cont;
}
+ /* Due to poor choice of crc32 seed, an all-zero node will have a correct CRC */
+ if (!je32_to_cpu(node->u.hdr_crc) && !je16_to_cpu(node->u.nodetype) &&
+ !je16_to_cpu(node->u.magic) && !je32_to_cpu(node->u.totlen)) {
+ JFFS2_NOTICE("All zero node header at %#08x.\n", ref_offset(ref));
+ jffs2_mark_node_obsolete(c, ref);
+ goto cont;
+ }
switch (je16_to_cpu(node->u.nodetype)) {