[ltt-dev] [UST PATCH 1/2] fix sscanf format string v2

[Mathieu Desnoyers]

* Douglas Santos (douglas.santos at polymtl.ca) wrote:
> Signed-off-by: Douglas Santos <douglas.santos at polymtl.ca>
> ---
>  libust/tracectl.c |   22 +++++++++++++++-------
>  1 files changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/libust/tracectl.c b/libust/tracectl.c
> index dd61ebe..b0a2daa 100644
> --- a/libust/tracectl.c
> +++ b/libust/tracectl.c
> @@ -529,7 +529,7 @@ static unsigned int pow2_higher_or_eq(unsigned int v)
>  static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *src)
>  {
>  	char *channel_slash_size;
> -	char ch_name[256]="";
> +	char *ch_name;
>  	unsigned int size, power;
>  	int retval = 0;
>  	struct ust_trace *trace;
> @@ -540,7 +540,7 @@ static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *sr
>  	DBG("set_subbuf_size");
>  
>  	channel_slash_size = nth_token(recvbuf, 1);
> -	sscanf(channel_slash_size, "%255[^/]/%u", ch_name, &size);
> +	sscanf(channel_slash_size, "%a[^/]/%u", &ch_name, &size);
>  
>  	if(ch_name == NULL) {
>  		ERR("cannot parse channel");
> @@ -578,6 +578,7 @@ static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *sr
>  	}
>  
>  	end:
> +	free(ch_name);

if you really want to deal with errors this way, please don't make the
code as error-prone as it is, and initialize:

char *ch_name = NULL;

at the beginning. So someone blindly adding one more test at the
beginning of the function which goto end; won't be hurt by uninitialized
variables.

>  	ltt_unlock_traces();
>  	return retval;
>  }
> @@ -585,7 +586,7 @@ static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *sr
>  static int do_cmd_set_subbuf_num(const char *recvbuf, struct ustcomm_source *src)
>  {
>  	char *channel_slash_num;
> -	char ch_name[256]="";
> +	char *ch_name;
>  	unsigned int num;
>  	int retval = 0;
>  	struct ust_trace *trace;
> @@ -596,7 +597,7 @@ static int do_cmd_set_subbuf_num(const char *recvbuf, struct ustcomm_source *src
>  	DBG("set_subbuf_num");
>  
>  	channel_slash_num = nth_token(recvbuf, 1);
> -	sscanf(channel_slash_num, "%255[^/]/%u", ch_name, &num);
> +	sscanf(channel_slash_num, "%a[^/]/%u", &ch_name, &num);
>  
>  	if(ch_name == NULL) {
>  		ERR("cannot parse channel");
> @@ -634,6 +635,7 @@ static int do_cmd_set_subbuf_num(const char *recvbuf, struct ustcomm_source *src
>  	}
>  
>  	end:
> +	free(ch_name);
>  	ltt_unlock_traces();
>  	return retval;
>  }
> @@ -1042,10 +1044,10 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  	}
>  	else if(nth_token_is(recvbuf, "enable_marker", 0) == 1) {
>  		char *channel_slash_name = nth_token(recvbuf, 1);
> -		char channel_name[256]="";
> -		char marker_name[256]="";
> +		char *channel_name;
> +		char *marker_name;
>  
> -		result = sscanf(channel_slash_name, "%255[^/]/%255s", channel_name, marker_name);
> +		result = sscanf(channel_slash_name, "%a[^/]/%as", &channel_name, &marker_name);
>  
>  		if(channel_name == NULL || marker_name == NULL) {
>  			WARN("invalid marker name");

what happens if either channel_name or marker_name != NULL ?

> @@ -1056,6 +1058,9 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  		if(result < 0) {
>  			WARN("could not enable marker; channel=%s, name=%s", channel_name, marker_name);
>  		}
> +
> +		free(channel_name);
> +		free(marker_name);
>  	}
>  	else if(nth_token_is(recvbuf, "disable_marker", 0) == 1) {
>  		char *channel_slash_name = nth_token(recvbuf, 1);
> @@ -1073,6 +1078,9 @@ int process_client_cmd(char *recvbuf, struct ustcomm_source *src)
>  		if(result < 0) {
>  			WARN("could not disable marker; channel=%s, name=%s", channel_name, marker_name);
>  		}
> +
> +		free(marker_name);
> +		free(channel_name);

same comment as above.

Thanks,

Mathieu

>  	}
>  	else if(nth_token_is(recvbuf, "get_pidunique", 0) == 1) {
>  		char *reply;
> -- 
> 1.7.0.4
> 
> 
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> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com