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authorDaniel P. Berrangé <berrange@redhat.com>2018-02-05 11:49:37 +0000
committerGerd Hoffmann <kraxel@redhat.com>2018-02-16 12:33:02 +0100
commitcf0706581bc0c24ab2e9a81ff0fc3efa9482c812 (patch)
treee3cb993a75f3bc55d57c64ab8a884418edc547f6 /ui/vnc.c
parent52c7c9d076dc64a6d3f1938b5a4994f84744c7fa (diff)
ui: check VNC audio frequency limit at time of reading from client
The 'vs->as.freq' value is a signed integer, which is read from an unsigned 32-bit int field on the wire. There is thus a risk of overflow on 32-bit platforms. Move the frequency limit checking to be done at time of read before casting to a signed integer. Reported-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Message-id: 20180205114938.15784-4-berrange@redhat.com Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'ui/vnc.c')
-rw-r--r--ui/vnc.c22
1 files changed, 13 insertions, 9 deletions
diff --git a/ui/vnc.c b/ui/vnc.c
index 746293ddfa..a77b568b57 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -982,14 +982,7 @@ static void vnc_update_throttle_offset(VncState *vs)
vs->client_width * vs->client_height * vs->client_pf.bytes_per_pixel;
if (vs->audio_cap) {
- int freq = vs->as.freq;
- /* We don't limit freq when reading settings from client, so
- * it could be upto MAX_INT in size. 48khz is a sensible
- * upper bound for trustworthy clients */
int bps;
- if (freq > 48000) {
- freq = 48000;
- }
switch (vs->as.fmt) {
default:
case AUD_FMT_U8:
@@ -1005,7 +998,7 @@ static void vnc_update_throttle_offset(VncState *vs)
bps = 4;
break;
}
- offset += freq * bps * vs->as.nchannels;
+ offset += vs->as.freq * bps * vs->as.nchannels;
}
/* Put a floor of 1MB on offset, so that if we have a large pending
@@ -2292,6 +2285,7 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len)
{
int i;
uint16_t limit;
+ uint32_t freq;
VncDisplay *vd = vs->vd;
if (data[0] > 3) {
@@ -2411,7 +2405,17 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len)
vnc_client_error(vs);
break;
}
- vs->as.freq = read_u32(data, 6);
+ freq = read_u32(data, 6);
+ /* No official limit for protocol, but 48khz is a sensible
+ * upper bound for trustworthy clients, and this limit
+ * protects calculations involving 'vs->as.freq' later.
+ */
+ if (freq > 48000) {
+ VNC_DEBUG("Invalid audio frequency %u > 48000", freq);
+ vnc_client_error(vs);
+ break;
+ }
+ vs->as.freq = freq;
break;
default:
VNC_DEBUG("Invalid audio message %d\n", read_u8(data, 4));