From a2ad7c21ad8cf1ce4ad65e13df1c2a1c29b38ac5 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 17 Jun 2020 23:01:23 +0100 Subject: [PATCH] rxrpc: Fix handling of rwind from an ACK packet The handling of the receive window size (rwind) from a received ACK packet is not correct. The rxrpc_input_ackinfo() function currently checks the current Tx window size against the rwind from the ACK to see if it has changed, but then limits the rwind size before storing it in the tx_winsize member and, if it increased, wake up the transmitting process. This means that if rwind > RXRPC_RXTX_BUFF_SIZE - 1, this path will always be followed. Fix this by limiting rwind before we compare it to tx_winsize. The effect of this can be seen by enabling the rxrpc_rx_rwind_change tracepoint. Fixes: 702f2ac87a9a ("rxrpc: Wake up the transmitter if Rx window size increases on the peer") Signed-off-by: David Howells --- net/rxrpc/input.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c index 299ac98e9754..767579328a06 100644 --- a/net/rxrpc/input.c +++ b/net/rxrpc/input.c @@ -722,13 +722,12 @@ static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb, ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU), rwind, ntohl(ackinfo->jumbo_max)); + if (rwind > RXRPC_RXTX_BUFF_SIZE - 1) + rwind = RXRPC_RXTX_BUFF_SIZE - 1; if (call->tx_winsize != rwind) { - if (rwind > RXRPC_RXTX_BUFF_SIZE - 1) - rwind = RXRPC_RXTX_BUFF_SIZE - 1; if (rwind > call->tx_winsize) wake = true; - trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, - ntohl(ackinfo->rwind), wake); + trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake); call->tx_winsize = rwind; }