76 lines
3.0 KiB
Diff
76 lines
3.0 KiB
Diff
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From f1e7ec03e26ab6b8ca9b7ec060846a5b706a963d 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: Disconnect when receiving overly big
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ClientMonitorsConfig
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Total message size received from the client was unlimited. There is
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a 2kiB size check on individual agent messages, but the MonitorsConfig
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message can be split in multiple chunks, and the size of the
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non-chunked MonitorsConfig message was never checked. This could easily
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lead to memory exhaustion on the host.
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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 | 25 +++++++++++++++++++++++--
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1 file changed, 23 insertions(+), 2 deletions(-)
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diff --git a/server/reds.c b/server/reds.c
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index f439a366..7be85fdf 100644
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--- a/server/reds.c
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+++ b/server/reds.c
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@@ -993,19 +993,34 @@ static void reds_client_monitors_config_cleanup(void)
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static void reds_on_main_agent_monitors_config(
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MainChannelClient *mcc, void *message, size_t size)
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{
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+ const unsigned int MAX_MONITORS = 256;
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+ const unsigned int MAX_MONITOR_CONFIG_SIZE =
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+ sizeof(VDAgentMonitorsConfig) + MAX_MONITORS * sizeof(VDAgentMonConfig);
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+
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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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+ // 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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+ if (sizeof(VDAgentMessage) + MAX_MONITOR_CONFIG_SIZE - cmc->buffer_size < size) {
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+ goto overflow;
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+ }
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cmc->buffer_size += size;
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cmc->buffer = realloc(cmc->buffer, cmc->buffer_size);
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spice_assert(cmc->buffer);
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cmc->mcc = mcc;
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memcpy(cmc->buffer + cmc->buffer_pos, message, size);
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cmc->buffer_pos += size;
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+ if (sizeof(VDAgentMessage) > cmc->buffer_size) {
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+ spice_debug("not enough data yet. %d", cmc->buffer_size);
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+ return;
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+ }
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msg_header = (VDAgentMessage *)cmc->buffer;
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- if (sizeof(VDAgentMessage) > cmc->buffer_size ||
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- msg_header->size > cmc->buffer_size - sizeof(VDAgentMessage)) {
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+ if (msg_header->size > MAX_MONITOR_CONFIG_SIZE) {
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+ goto overflow;
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+ }
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+ if (msg_header->size > cmc->buffer_size - sizeof(VDAgentMessage)) {
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spice_debug("not enough data yet. %d", cmc->buffer_size);
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return;
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}
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@@ -1013,6 +1028,12 @@ static void reds_on_main_agent_monitors_config(
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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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+ return;
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+
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+overflow:
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+ spice_warning("received invalid MonitorsConfig request from client, disconnecting");
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+ red_channel_client_disconnect(main_channel_client_get_base(mcc));
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+ reds_client_monitors_config_cleanup();
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}
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void reds_on_main_agent_data(MainChannelClient *mcc, void *message, size_t size)
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--
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2.11.0
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