[PATCH 3.16 140/328] ubifs: Check data node size before truncate

Ben Hutchings
2018-12-09T22:26:24Z

From: Richard Weinberger <richard@nod.at>

commit 95a22d2084d72ea067d8323cc85677dba5d97cae upstream.

Check whether the size is within bounds before using it.
If the size is not correct, abort and dump the bad data node.

Cc: Kees Cook <keescook@chromium.org>
Cc: Silvio Cesare <silvio.cesare@gmail.com>
Fixes: 1e51764a3c2ac ("UBIFS: add new flash file system")
Reported-by: Silvio Cesare <silvio.cesare@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
[bwh: Backported to 3.16: Drop first argument to ubifs_err()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/ubifs/journal.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -1186,7 +1186,16 @@ int ubifs_jnl_truncate(struct ubifs_info
else if (err)
goto out_free;
else {
- if (le32_to_cpu(dn->size) <= dlen)
+ int dn_len = le32_to_cpu(dn->size);
+
+ if (dn_len <= 0 || dn_len > UBIFS_BLOCK_SIZE) {
+ ubifs_err("bad data node (block %u, inode %lu)",
+ blk, inode->i_ino);
+ ubifs_dump_node(c, dn);
+ goto out_free;
+ }
+
+ if (dn_len <= dlen)
dlen = 0; /* Nothing to do */
else {
int compr_type = le16_to_cpu(dn->compr_type);