From 762e0abae36033ccde658fd52d3235887b60862d Mon Sep 17 00:00:00 2001
From: Frediano Ziglio <freddy77@gmail.com>
Date: Wed, 29 Apr 2020 15:09:13 +0100
Subject: [PATCH spice-common 1/4] quic: Check we have some data to start
 decoding quic image

All paths already pass some data to quic_decode_begin but for the
test check it, it's not that expensive test.
Checking for not 0 is enough, all other words will potentially be
read calling more_io_words but we need one to avoid a potential
initial buffer overflow or deferencing an invalid pointer.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>
Acked-by: Uri Lublin <uril@redhat.com>
---
 spice-common/common/quic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/common/quic.c b/common/quic.c
index e2dee0f..bc753ca 100644
--- a/spice-common/common/quic.c
+++ b/spice-common/common/quic.c
@@ -1136,7 +1136,7 @@ int quic_decode_begin(QuicContext *quic, uint32_t *io_ptr, unsigned int num_io_w
     int channels;
     int bpc;
 
-    if (!encoder_reset(encoder, io_ptr, io_ptr_end)) {
+    if (!num_io_words || !encoder_reset(encoder, io_ptr, io_ptr_end)) {
         return QUIC_ERROR;
     }
 
-- 
2.25.4

