The patch below does not apply to the 3.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 95a22d2084d72ea067d8323cc85677dba5d97cae Mon Sep 17 00:00:00 2001
From: Richard Weinberger richard@nod.at Date: Sun, 1 Jul 2018 23:20:51 +0200 Subject: [PATCH] ubifs: Check data node size before truncate
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 Cc: stable@vger.kernel.org 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
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c index 1406765c3ef9..cef0d76d490a 100644 --- a/fs/ubifs/journal.c +++ b/fs/ubifs/journal.c @@ -1393,7 +1393,16 @@ int ubifs_jnl_truncate(struct ubifs_info *c, const struct inode *inode, 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(c, "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 { err = truncate_data_node(c, inode, blk, dn, &dlen);