From: Michal Bloch <m.bloch@samsung.com>
Date: Wed, 16 Aug 2017 12:08:19 +0000 (+0200)
Subject: logger: handle logs of odd length correctly
X-Git-Tag: submit/tizen/20170816.150837^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=154c5eaaf1ecf6224de0bcafc872c4952ffdae9b;p=platform%2Fcore%2Fsystem%2Fdlog.git

logger: handle logs of odd length correctly

If there was only one byte left before the buffer wraps around,
the length field, which consists of 2 bytes, would end up torn apart,
yielding garbage on naive read attempts.

While libdlog did ensure to write only even-length logs, this could
not be relied upon when not using it: this includes kmsg and, potentially,
malicious users.

Change-Id: I7ec3777d650ec2642812b27e87de5e16e0dd72fc
Signed-off-by: Michal Bloch <m.bloch@samsung.com>
---

diff --git a/src/logger/logger.c b/src/logger/logger.c
index 39afcd5..87663ec 100644
--- a/src/logger/logger.c
+++ b/src/logger/logger.c
@@ -899,8 +899,10 @@ static int print_out_logs(struct logger *server, struct reader *reader)
 	}
 
 	while (from != buffer->tail && (!reader->dumpcount || (reader->bytes_to_read > 0))) {
-		ple = (struct logger_entry*)(buffer->buffer + from);
-		copy_from_buffer(tmp, from, ple->len, buffer);
+		typeof(ple->len) length;
+		copy_from_buffer(&length, from, sizeof length, buffer);
+
+		copy_from_buffer(tmp, from, length, buffer);
 		ple = (struct logger_entry*)tmp;
 
 		from += ple->len;