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Don't crash for ERSPAN packets in Linux cooked captures. 

Sadly, "cooked" means the GRE header isn't available; the extra data
pointer is null, so we can't dereference it.

Bug: 14548
Change-Id: I51ae67dcc144b7f5ab3c82dd9adf09b342b29ced
Reviewed-on: https://code.wireshark.org/review/26595
Reviewed-by: Guy Harris <guy@alum.mit.edu>
This commit is contained in:
Guy Harris 2018-03-22 14:15:42 -07:00
parent c55d15783c
commit 1ea82e4ff7
2 changed files with 22 additions and 3 deletions
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17
epan/dissectors/packet-cisco-erspan.c
View File

@ -133,12 +133,23 @@ dissect_erspan(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
tvbuff_t *eth_tvb;
guint32 offset = 0;
guint16 version;
guint16 gre_flags_and_ver = *(guint16 *)data;
if(gre_flags_and_ver == 0) {
if (data == NULL) {
/*
* We weren't handed the GRE flags or version.
*
* This can happen if a Linux cooked capture is done and
* we get a packet from an "ipgre" interface.
*/
version = G_MAXUINT16; /* Possible values are 0...15 */
} else {
version = tvb_get_ntohs(tvb, offset) >> 12;
guint16 gre_flags_and_ver = *(guint16 *)data;
if (gre_flags_and_ver == 0) {
version = G_MAXUINT16; /* Possible values are 0...15 */
} else {
version = tvb_get_ntohs(tvb, offset) >> 12;
}
}
ti = proto_tree_add_item(tree, proto_erspan, tvb, offset, -1,

8
epan/dissectors/packet-sll.c
View File

@ -347,6 +347,14 @@ dissect_sll(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
} else {
switch (hatype) {
case ARPHRD_IPGRE:
/*
* XXX - the link-layer header appears to consist
* of an IPv4 header followed by a bunch of stuff
* that includes the GRE flags and version, but
* cooked captures strip the link-layer header,
* so we can't provide the flags and version to
* the dissector.
*/
proto_tree_add_uint(fh_tree, &hfi_sll_gretype, tvb, 14, 2,
protocol);
dissector_try_uint(gre_dissector_table,