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[Full-disclosure] Step-by-step instructions for debugging Cisco IOS using gdb

From: Smiler S <smiler808_at_nospam>
Date: Fri Aug 15 2008 - 18:20:18 GMT
To: full-disclosure@lists.grok.org.uk


 From: Andy Davis
<iosftpexploit_at_googlemail.com<iosftpexploit_at_googlemail.com?Subject=Re:%20Step-by-step%20instructions%20for%20debugging%20Cisco%20IOS%20using%20gdb>>

Date: Tue, 12 Aug 2008 22:01:37 +0100

>Congratulations you are now debugging IOS ;-)
>One unusual feature, which I have yet to explain is that when the
>registers are displayed they are all offset by 1 e.g:

If a vector variable is stored in a register, gcc writes debug information telling gdb which register the variable is stored in. This mapping is changed between gcc2 & gcc3. Since there isn't anything in the debug output to distinguish code compiled by gcc3 from code compiled by gcc2, there is no way for gdb to know the right map. gdb supports the gcc3 map.

If vector code is compiled by gcc2 as in the case of IOS, then the register assignment will be off by 1.

PS - Stop ripping Gyan and Varuns IOS research work you jackass cause you ain't getting no fame with that bullshit :P :P :P



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