[PATCH v1 1/1] xlog: fix out of static memory on metadata load

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

This problem triggered asan checks on start tarantool
with existent xlog. We don't have to touch even static
non-initialized memory.
---
Branch: http://github.com/tarantool/tarantool/tree/kshch/vinyl-xlog-out-of-static-memory

 src/box/xlog.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/box/xlog.c b/src/box/xlog.c
index 5ed11fc..797f153 100644
--- a/src/box/xlog.c
+++ b/src/box/xlog.c
@@ -261,8 +261,11 @@ xlog_meta_parse(struct xlog_meta *meta, const char **data,
 		assert(val <= val_end);
 		pos = eol + 1;
 
-		if (memcmp(key, INSTANCE_UUID_KEY, key_end - key) == 0 ||
-		    memcmp(key, INSTANCE_UUID_KEY_V12, key_end - key) == 0) {
+		size_t len = key_end - key;
+		if ((len == strlen(INSTANCE_UUID_KEY) &&
+		    memcmp(key, INSTANCE_UUID_KEY, len) == 0) ||
+		    (len == strlen(INSTANCE_UUID_KEY_V12) &&
+		    memcmp(key, INSTANCE_UUID_KEY_V12, key_end - key) == 0)) {
 			/*
 			 * Instance: <uuid>
 			 */
@@ -277,19 +280,22 @@ xlog_meta_parse(struct xlog_meta *meta, const char **data,
 				diag_set(XlogError, "can't parse instance UUID");
 				return -1;
 			}
-		} else if (memcmp(key, VCLOCK_KEY, key_end - key) == 0){
+		} else if (len == strlen(VCLOCK_KEY) &&
+			   memcmp(key, VCLOCK_KEY, len) == 0) {
 			/*
 			 * VClock: <vclock>
 			 */
 			if (parse_vclock(val, val_end, &meta->vclock) != 0)
 				return -1;
-		} else if (memcmp(key, PREV_VCLOCK_KEY, key_end - key) == 0) {
+		} else if (len == strlen(PREV_VCLOCK_KEY) &&
+			   memcmp(key, PREV_VCLOCK_KEY, len) == 0) {
 			/*
 			 * PrevVClock: <vclock>
 			 */
 			if (parse_vclock(val, val_end, &meta->prev_vclock) != 0)
 				return -1;
-		} else if (memcmp(key, VERSION_KEY, key_end - key) == 0) {
+		} else if (len == strlen(VERSION_KEY) &&
+			   memcmp(key, VERSION_KEY, len) == 0) {
 			/* Ignore Version: for now */
 		} else {
 			/*
-- 
2.7.4