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Commit 0ce4e70f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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net: dccp: switch rx_tstamp_last_feedback to monotonic clock 



To compute delays, better not use time of the day which can
be changed by admins or malicious programs.

Also change ccid3_first_li() to use s64 type for delta variable
to avoid potential overflows.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Cc: dccp@vger.kernel.org
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 74174fe5

net/dccp/ccids/ccid3.c

+7 −4
Original line number Diff line number Diff line
@@ -600,7 +600,7 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk, 
{

	struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);

	struct dccp_sock *dp = dccp_sk(sk);

	ktime_t now = ktime_get_real();

	ktime_t now = ktime_get();

	s64 delta = 0;



	switch (fbtype) {
@@ -632,7 +632,7 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk, 
		return;

	}



	ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta,

	ccid3_pr_debug("Interval %lldusec, X_recv=%u, 1/p=%u\n", delta,

		       hc->rx_x_recv, hc->rx_pinv);



	hc->rx_tstamp_last_feedback = now;
@@ -679,7 +679,8 @@ static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) 
static u32 ccid3_first_li(struct sock *sk)

{

	struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);

	u32 x_recv, p, delta;

	u32 x_recv, p;

	s64 delta;

	u64 fval;



	if (hc->rx_rtt == 0) {
@@ -687,7 +688,9 @@ static u32 ccid3_first_li(struct sock *sk) 
		hc->rx_rtt = DCCP_FALLBACK_RTT;

	}



	delta  = ktime_to_us(net_timedelta(hc->rx_tstamp_last_feedback));

	delta = ktime_us_delta(ktime_get(), hc->rx_tstamp_last_feedback);

	if (delta <= 0)

		delta = 1;

	x_recv = scaled_div32(hc->rx_bytes_recv, delta);

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

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