[Spice-devel] [PATCH spice-common 2/6] quic: Check image size in quic_decode_begin

[Frediano Ziglio]

From: Frediano Ziglio <freddy77 at gmail.com>

Avoid some overflow in code due to images too big or
negative numbers.

Signed-off-by: Frediano Ziglio <freddy77 at gmail.com>
Acked-by: Uri Lublin <uril at redhat.com>
---
 common/quic.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/common/quic.c b/common/quic.c
index bc753ca..6815316 100644
--- a/common/quic.c
+++ b/common/quic.c
@@ -56,6 +56,9 @@ typedef uint8_t BYTE;
 #define MINwminext 1
 #define MAXwminext 100000000
 
+/* Maximum image size in pixels, mainly to avoid possible integer overflows */
+#define SPICE_MAX_IMAGE_SIZE (512 * 1024 * 1024 - 1)
+
 typedef struct QuicFamily {
     unsigned int nGRcodewords[MAXNUMCODES];      /* indexed by code number, contains number of
                                                     unmodified GR codewords in the code */
@@ -1165,6 +1168,16 @@ int quic_decode_begin(QuicContext *quic, uint32_t *io_ptr, unsigned int num_io_w
     height = encoder->io_word;
     decode_eat32bits(encoder);
 
+    if (width <= 0 || height <= 0) {
+        encoder->usr->warn(encoder->usr, "invalid size\n");
+        return QUIC_ERROR;
+    }
+
+    /* avoid too big images */
+    if ((uint64_t) width * height > SPICE_MAX_IMAGE_SIZE) {
+        encoder->usr->error(encoder->usr, "image too large\n");
+    }
+
     quic_image_params(encoder, type, &channels, &bpc);
 
     if (!encoder_reset_channels(encoder, channels, width, bpc)) {
-- 
2.26.2