Wireshark · Wireshark-bugs: [Wireshark-bugs] [Bug 8603] New: Endless loop in vnc_hextile_encoding

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Bug ID	8603
Summary	Endless loop in vnc_hextile_encoding
Classification	Unclassified
Product	Wireshark
Version	1.8.6
Hardware	All
OS	All
Status	UNCONFIRMED
Severity	Normal
Priority	Low
Component	Dissection engine (libwireshark)
Assignee	bugzilla-admin@wireshark.org
Reporter	pevaneyn@cisco.com

Created attachment 10635 [details]
patch for the infinite loop in vnc_hextile_encoding

Build Information:

--
Hi,

While investigating a capture wireshark hung. Investigating it turned out that
in epan/dissectors/packet-vnc.c:vnc_hextile_encoding num_subrects was actually
256.

As we have "for(i = 0; i < num_subrects; i++) {" this made for a nice infinite
loop.

I did a stupid fix: 

diff --git a/epan/dissectors/packet-vnc.c b/epan/dissectors/packet-vnc.c
index 2da117a..83147f9 100644
--- a/epan/dissectors/packet-vnc.c
+++ b/epan/dissectors/packet-vnc.c
@@ -1896,8 +1896,8 @@ vnc_hextile_encoding(tvbuff_t *tvb, packet_info *pinfo,
gint *offset,
                     proto_tree *tree, const guint16 width, const guint16
height)
 {
        guint8      bytes_per_pixel = vnc_get_bytes_per_pixel(pinfo);
-       guint8      i, subencoding_mask, num_subrects, subrect_len,
tile_height, tile_width;
-       guint32     raw_length;
+       guint8      subencoding_mask, num_subrects, subrect_len, tile_height,
tile_width;
+       guint32     i, raw_length;
        proto_tree *tile_tree, *subencoding_mask_tree, *subrect_tree,
*num_subrects_tree;
        proto_item *ti, *tile_item;
        guint16     current_height  = 0, current_width;

which fixed the loop by making 'i' 32 bit.

The patched version worked without problem.

As the capture contains customer information I fear that I cannot attach it.
Sorry.

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