159 lines
6.2 KiB
Diff
159 lines
6.2 KiB
Diff
Fix CVE-2017-7506:
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https://bugzilla.redhat.com/show_bug.cgi?id=1452606
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https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7506
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Patches copied from Debian spice package version
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'spice_0.12.8-2.1+deb9u1.debian.tar.xz':
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http://security.debian.org/debian-security/pool/updates/main/s/spice/spice_0.12.8-2.1+deb9u1.debian.tar.xz
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The patches had to be adapted to apply to the latest spice tarball, and
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are based on these upstream commits:
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https://cgit.freedesktop.org/spice/spice/commit/?id=111ab38611cef5012f1565a65fa2d8a8a05cce37
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https://cgit.freedesktop.org/spice/spice/commit/?id=571cec91e71c2aae0d5f439ea2d8439d0c3d75eb
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https://cgit.freedesktop.org/spice/spice/commit/?id=fbbcdad773e2791cfb988f4748faa41943551ca6
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From 257f69d619fed407493156c8a7b952abc8a51314 Mon Sep 17 00:00:00 2001
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Date: Mon, 15 May 2017 15:57:28 +0100
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Subject: [spice-server 1/3] 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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---
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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 f439a3668..7be85fdfc 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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2.13.0
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From ff2b4ef70181087d5abd50bad76d026ec5088a93 Mon Sep 17 00:00:00 2001
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Date: Mon, 15 May 2017 15:57:28 +0100
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Subject: [spice-server 2/3] reds: Avoid integer overflows handling monitor
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configuration
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Avoid VDAgentMessage::size integer overflows.
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---
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server/reds.c | 3 +++
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1 file changed, 3 insertions(+)
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diff --git a/server/reds.c b/server/reds.c
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index 7be85fdfc..e1c8c1086 100644
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--- a/server/reds.c
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+++ b/server/reds.c
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@@ -1024,6 +1024,9 @@ static void reds_on_main_agent_monitors_config(
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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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+ if (msg_header->size < sizeof(VDAgentMonitorsConfig)) {
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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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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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--
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2.13.0
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From 8cc3d7df2792751939cc832f4110c57e2addfca5 Mon Sep 17 00:00:00 2001
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Date: Mon, 15 May 2017 15:57:28 +0100
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Subject: [spice-server 3/3] 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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---
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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 e1c8c1086..3a42c3755 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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2.13.0
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