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rxrpc: Fix handling of rwind from an ACK packet 

[ Upstream commit a2ad7c21ad ]

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: 702f2ac87a ("rxrpc: Wake up the transmitter if Rx window size increases on the peer")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
David Howells 2020-06-17 23:01:23 +01:00 committed by Sasha Levin
parent 73cff44e66
commit d6fb7f4574
1 changed files with 3 additions and 4 deletions
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7
net/rxrpc/input.c
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@ -723,13 +723,12 @@ 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;
}