61 lines
1.8 KiB
Diff
61 lines
1.8 KiB
Diff
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From 1c6517973095a67c8cb57f3550fc1298404ab556 Mon Sep 17 00:00:00 2001
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From: Frediano Ziglio <fziglio@redhat.com>
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Date: Tue, 13 Dec 2016 14:39:48 +0000
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Subject: [PATCH] Prevent possible DoS attempts during protocol handshake
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The limit for link message is specified using a 32 bit unsigned integer.
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This could cause possible DoS due to excessive memory allocations and
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some possible crashes.
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For instance a value >= 2^31 causes a spice_assert to be triggered in
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async_read_handler (reds-stream.c) due to an integer overflow at this
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line:
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int n = async->end - async->now;
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This could be easily triggered with a program like
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#!/usr/bin/env python
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import socket
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import time
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from struct import pack
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server = '127.0.0.1'
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port = 5900
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s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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s.connect((server, port))
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data = pack('<4sIII', 'REDQ', 2, 2, 0xaaaaaaaa)
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s.send(data)
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time.sleep(1)
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without requiring any authentication (the same can be done
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with TLS).
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[Peter: fixes CVE-2016-9578]
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Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
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Acked-by: Christophe Fergeau <cfergeau@redhat.com>
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Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
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---
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server/reds.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/server/reds.c b/server/reds.c
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index f40b65c1..86a33d53 100644
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--- a/server/reds.c
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+++ b/server/reds.c
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@@ -2202,7 +2202,8 @@ static void reds_handle_read_header_done(void *opaque)
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reds->peer_minor_version = header->minor_version;
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- if (header->size < sizeof(SpiceLinkMess)) {
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+ /* the check for 4096 is to avoid clients to cause arbitrary big memory allocations */
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+ if (header->size < sizeof(SpiceLinkMess) || header->size > 4096) {
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reds_send_link_error(link, SPICE_LINK_ERR_INVALID_DATA);
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spice_warning("bad size %u", header->size);
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reds_link_free(link);
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--
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2.11.0
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