From: Yue Hu <huyue2@yulong.com>
Date: Fri, 1 Feb 2019 03:27:32 +0000 (+0800)
Subject: pstore/ram: Add kmsg hlen zero check to ramoops_pstore_write()
X-Git-Tag: v5.1-rc1~97^2~1
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=47afd7ae65c737bfef67e9eb1424723d13b06787;p=linux.git

pstore/ram: Add kmsg hlen zero check to ramoops_pstore_write()

If zero-length header happened in ramoops_write_kmsg_hdr(), that means
we will not be able to read back dmesg record later, since it will be
treated as invalid header in ramoops_pstore_read(). So we should not
execute the following code but return the error.

Signed-off-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index d06e2f3e3bec..ec0e1da0596a 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -425,6 +425,9 @@ static int notrace ramoops_pstore_write(struct pstore_record *record)
 
 	/* Build header and append record contents. */
 	hlen = ramoops_write_kmsg_hdr(prz, record);
+	if (!hlen)
+		return -ENOMEM;
+
 	size = record->size;
 	if (size + hlen > prz->buffer_size)
 		size = prz->buffer_size - hlen;