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ssh: apply post-release patch from V_9_0 branch

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upstream: clear io_want/io_ready flags at start of poll() cycle;

avoids plausible spin during rekeying if channel io_want flags are reused
across cycles. ok markus@ deraadt@
This commit is contained in:
Ed Maste 2022-04-15 11:03:08 -04:00
parent fb5aabcb99
commit 9fce8d4140
1 changed files with 7 additions and 2 deletions
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9
crypto/openssh/channels.c
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@ -1,4 +1,4 @@
/* $OpenBSD: channels.c,v 1.415 2022/03/30 21:10:25 djm Exp $ */
/* $OpenBSD: channels.c,v 1.416 2022/04/11 22:52:08 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -2601,7 +2601,12 @@ channel_prepare_poll(struct ssh *ssh, struct pollfd **pfdp, u_int *npfd_allocp,
u_int i, oalloc, p, npfd = npfd_reserved;
channel_before_prepare_io(ssh); /* might create a new channel */
/* clear out I/O flags from last poll */
for (i = 0; i < sc->channels_alloc; i++) {
if (sc->channels[i] == NULL)
continue;
sc->channels[i]->io_want = sc->channels[i]->io_ready = 0;
}
/* Allocate 4x pollfd for each channel (rfd, wfd, efd, sock) */
if (sc->channels_alloc >= (INT_MAX / 4) - npfd_reserved)
fatal_f("too many channels"); /* shouldn't happen */