Commit 0f9e5b57 authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
Browse files

[DCCP]: Debug timeval operations 



Problem:

 Most target types in the CCID3 code are u32, so subtle conversion errors
 can occur if signed time calculations yield negative results: the original
 values are lost in the conversion to unsigned, calculation errors go undetected.

 This patch therefore
   * sets all critical time types from unsigned to suseconds_t
   * avoids comparison between signed/unsigned via type-casting
   * provides ample warning messages in case time calculations are negative

 These warning messages can be removed at a later stage when the code
 has undergone more testing.

Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@mandriva.com>
parent bfe24a6c

net/dccp/ccids/ccid3.c

+32 −24
Original line number Diff line number Diff line
@@ -128,8 +128,8 @@ static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now) 
		hctx->ccid3hctx_x = max_t(u64, hctx->ccid3hctx_x,

					  (hctx->ccid3hctx_s << 6)/TFRC_T_MBI);



	} else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) >=

							  hctx->ccid3hctx_rtt) {

	} else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) -

			(suseconds_t)hctx->ccid3hctx_rtt >= 0 ) {



		hctx->ccid3hctx_x = max(2 * min(hctx->ccid3hctx_x,

						hctx->ccid3hctx_x_recv),
@@ -271,7 +271,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	struct dccp_tx_hist_entry *new_packet;

	struct timeval now;

	long delay;

	suseconds_t delay;



	BUG_ON(hctx == NULL);
@@ -331,7 +331,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 
		 * else

		 *       // send the packet in (t_nom - t_now) milliseconds.

		 */

		if (delay - (long)hctx->ccid3hctx_delta >= 0)

		if (delay - (suseconds_t)hctx->ccid3hctx_delta >= 0)

			return delay / 1000L;

		break;

	case TFRC_SSTATE_TERM:
@@ -353,7 +353,7 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len) 
	const struct dccp_sock *dp = dccp_sk(sk);

	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	struct timeval now;

	unsigned long quarter_rtt;

	suseconds_t quarter_rtt;

	struct dccp_tx_hist_entry *packet;



	BUG_ON(hctx == NULL);
@@ -450,10 +450,8 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 
		r_sample  = timeval_delta(&now, &packet->dccphtx_tstamp);

		t_elapsed = dp->dccps_options_received.dccpor_elapsed_time * 10;



		if (unlikely(r_sample <= 0)) {

			DCCP_WARN("WARNING: R_sample (%ld) <= 0!\n", r_sample);

			r_sample = 0;

		} else if (unlikely(r_sample <= t_elapsed))

		DCCP_BUG_ON(r_sample < 0);

		if (unlikely(r_sample <= t_elapsed))

			DCCP_WARN("WARNING: r_sample=%ldus <= t_elapsed=%ldus\n",

				  r_sample, t_elapsed);

		else
@@ -698,6 +696,7 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk) 
	struct dccp_sock *dp = dccp_sk(sk);

	struct dccp_rx_hist_entry *packet;

	struct timeval now;

	suseconds_t delta;



	ccid3_pr_debug("%s, sk=%p\n", dccp_role(sk), sk);
@@ -707,12 +706,12 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk) 
	case TFRC_RSTATE_NO_DATA:

		hcrx->ccid3hcrx_x_recv = 0;

		break;

	case TFRC_RSTATE_DATA: {

		const u32 delta = timeval_delta(&now,

	case TFRC_RSTATE_DATA:

		delta = timeval_delta(&now,

				      &hcrx->ccid3hcrx_tstamp_last_feedback);

		DCCP_BUG_ON(delta < 0);

		hcrx->ccid3hcrx_x_recv =

			scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);

	}

		break;

	case TFRC_RSTATE_TERM:

		DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
@@ -730,9 +729,10 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk) 
	hcrx->ccid3hcrx_ccval_last_counter   = packet->dccphrx_ccval;

	hcrx->ccid3hcrx_bytes_recv	     = 0;



	/* Convert to multiples of 10us */

	hcrx->ccid3hcrx_elapsed_time =

			timeval_delta(&now, &packet->dccphrx_tstamp) / 10;

	/* Elapsed time information [RFC 4340, 13.2] in units of 10 * usecs */

	delta = timeval_delta(&now, &packet->dccphrx_tstamp);

	DCCP_BUG_ON(delta < 0);

	hcrx->ccid3hcrx_elapsed_time = delta / 10;



	if (hcrx->ccid3hcrx_p == 0)

		hcrx->ccid3hcrx_pinv = ~0U;	/* see RFC 4342, 8.5 */
@@ -785,7 +785,8 @@ static u32 ccid3_hc_rx_calc_first_li(struct sock *sk) 
{

	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);

	struct dccp_rx_hist_entry *entry, *next, *tail = NULL;

	u32 rtt, delta, x_recv, p;

	u32 x_recv, p;

	suseconds_t rtt, delta;

	struct timeval tstamp = { 0, };

	int interval = 0;

	int win_count = 0;
@@ -830,8 +831,12 @@ found: 
		DCCP_CRIT("tail is null\n");

		return ~0;

	}

	rtt = timeval_delta(&tstamp, &tail->dccphrx_tstamp) * 4 / interval;

	ccid3_pr_debug("%s, sk=%p, approximated RTT to %uus\n",



	delta = timeval_delta(&tstamp, &tail->dccphrx_tstamp);

	DCCP_BUG_ON(delta < 0);



	rtt = delta * 4 / interval;

	ccid3_pr_debug("%s, sk=%p, approximated RTT to %ldus\n",

		       dccp_role(sk), sk, rtt);



	/*
@@ -849,8 +854,9 @@ found: 


	dccp_timestamp(sk, &tstamp);

	delta = timeval_delta(&tstamp, &hcrx->ccid3hcrx_tstamp_last_feedback);

	x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);

	DCCP_BUG_ON(delta <= 0);



	x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);

	if (x_recv == 0) {		/* would also trigger divide-by-zero */

		DCCP_WARN("X_recv==0\n");

		if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
@@ -977,7 +983,8 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 
	const struct dccp_options_received *opt_recv;

	struct dccp_rx_hist_entry *packet;

	struct timeval now;

	u32 p_prev, rtt_prev, r_sample, t_elapsed;

	u32 p_prev, rtt_prev;

	suseconds_t r_sample, t_elapsed;

	int loss, payload_size;



	BUG_ON(hcrx == NULL);
@@ -997,8 +1004,9 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 
		r_sample = timeval_usecs(&now);

		t_elapsed = opt_recv->dccpor_elapsed_time * 10;



		DCCP_BUG_ON(r_sample < 0);

		if (unlikely(r_sample <= t_elapsed))

			DCCP_WARN("r_sample=%uus, t_elapsed=%uus\n",

			DCCP_WARN("r_sample=%ldus, t_elapsed=%ldus\n",

				  r_sample, t_elapsed);

		else

			r_sample -= t_elapsed;
@@ -1051,8 +1059,8 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 
			break;



		dccp_timestamp(sk, &now);

		if (timeval_delta(&now, &hcrx->ccid3hcrx_tstamp_last_ack) >=

		    hcrx->ccid3hcrx_rtt) {

		if (timeval_delta(&now, &hcrx->ccid3hcrx_tstamp_last_ack) -

					(suseconds_t)hcrx->ccid3hcrx_rtt >= 0) {

			hcrx->ccid3hcrx_tstamp_last_ack = now;

			ccid3_hc_rx_send_feedback(sk);

		}

net/dccp/dccp.h

+1 −0
Original line number Diff line number Diff line
@@ -432,6 +432,7 @@ static inline void timeval_sub_usecs(struct timeval *tv, 
		tv->tv_sec--;

		tv->tv_usec += USEC_PER_SEC;

	}

	DCCP_BUG_ON(tv->tv_sec < 0);

}



#ifdef CONFIG_SYSCTL

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