49 lines
1.9 KiB
Diff
49 lines
1.9 KiB
Diff
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From a957a90baf2c62d31f3547e56bba7d0e812d2331 Mon Sep 17 00:00:00 2001
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From: Frediano Ziglio <fziglio@redhat.com>
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Date: Mon, 15 May 2017 15:57:28 +0100
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Subject: [PATCH] reds: Avoid buffer overflows handling monitor
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configuration
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It was also possible for a malicious client to set
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VDAgentMonitorsConfig::num_of_monitors to a number larger
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than the actual size of VDAgentMOnitorsConfig::monitors.
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This would lead to buffer overflows, which could allow the guest to
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read part of the host memory. This might cause write overflows in the
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host as well, but controlling the content of such buffers seems
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complicated.
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Signed-off-by: Frediano Ziglio <fziglio@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 | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/server/reds.c b/server/reds.c
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index e1c8c108..3a42c375 100644
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--- a/server/reds.c
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+++ b/server/reds.c
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@@ -1000,6 +1000,7 @@ static void reds_on_main_agent_monitors_config(
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VDAgentMessage *msg_header;
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VDAgentMonitorsConfig *monitors_config;
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RedsClientMonitorsConfig *cmc = &reds->client_monitors_config;
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+ uint32_t max_monitors;
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// limit size of message sent by the client as this can cause a DoS through
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// memory exhaustion, or potentially some integer overflows
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@@ -1028,6 +1029,12 @@ static void reds_on_main_agent_monitors_config(
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goto overflow;
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}
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monitors_config = (VDAgentMonitorsConfig *)(cmc->buffer + sizeof(*msg_header));
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+ // limit the monitor number to avoid buffer overflows
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+ max_monitors = (msg_header->size - sizeof(VDAgentMonitorsConfig)) /
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+ sizeof(VDAgentMonConfig);
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+ if (monitors_config->num_of_monitors > max_monitors) {
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+ goto overflow;
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+ }
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spice_debug("%s: %d", __func__, monitors_config->num_of_monitors);
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red_dispatcher_client_monitors_config(monitors_config);
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reds_client_monitors_config_cleanup();
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--
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2.11.0
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