Wireshark-bugs: [Wireshark-bugs] [Bug 8168] NAS-EPS_plain: wrong message decoding
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From: bugzilla-daemon@xxxxxxxxxxxxx
Date: Mon, 07 Jan 2013 14:12:34 +0000

Comment # 2 on bug 8168 from 
Hi Jerome,

are you facing the issue because of a plain ESM message having a EPS bearer
identity set to 12 or bigger?

Your proposal to remove this code part is not correct either as it would
prevent to decode a EMM Service Request message when in plain mode.

As in plain mode the 4MSB are either a security header type (for EMM messages)
or a EPS bearer identity (for ESM messages), I would prefer to tighten the test
by checking both the security header type and the protocol discriminator.

Replacing:
    /* SERVICE REQUEST (security header type equal to 12 or greater) is not a
plain NAS message */
    pd = tvb_get_guint8(tvb,offset);
    if (pd >= 0xc0) {
by
    /* SERVICE REQUEST (security header type equal to 12 or greater) is not a
plain NAS message */
    pd = tvb_get_guint8(tvb,offset);
    if (((pd&0xf0) >= 0xc0) && ((pd&0x0f) == 0x07)) {

Should fix everything.

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