[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH 3/4] ui: check VNC audio frequency limit at time of
From: |
Daniel P . Berrangé |
Subject: |
[Qemu-devel] [PATCH 3/4] ui: check VNC audio frequency limit at time of reading from client |
Date: |
Mon, 5 Feb 2018 11:49:37 +0000 |
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 <address@hidden>
Signed-off-by: Daniel P. Berrangé <address@hidden>
---
ui/vnc.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/ui/vnc.c b/ui/vnc.c
index e14e524764..79ac9eccde 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
@@ -2279,6 +2272,7 @@ 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) {
@@ -2398,7 +2392,17 @@ 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));
--
2.14.3