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

[Vladimir Davydov <vdavydov.dev@gmail.com>]

On Wed, Aug 15, 2018 at 03:32:02PM +0300, Kirill Shcherbatov wrote:
> 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)) {

Too much of code duplication. Please add a helper for key matching.

>  			/*
>  			 * 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 {
>  			/*