This is a note to let you know that I've just added the patch titled rxrpc: Fix handling of rwind from an ACK packet to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rxrpc-fix-handling-of-rwind-from-an-ack-packet.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d77a8b2c1b67a15899110ba98c12d84d6db2c29a Author: David Howells <dhowells@xxxxxxxxxx> Date: Wed Jun 17 23:01:23 2020 +0100 rxrpc: Fix handling of rwind from an ACK packet [ Upstream commit a2ad7c21ad8cf1ce4ad65e13df1c2a1c29b38ac5 ] 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 <dhowells@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c index e65b230fce4c4..58bd558a277a4 100644 --- a/net/rxrpc/input.c +++ b/net/rxrpc/input.c @@ -735,13 +735,12 @@ 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; }