dropbearconvert crashes converting 8192-bit RSA OpenSSH host key to dropbear format

Matt Johnston matt at ucc.asn.au
Mon Feb 9 22:55:17 AWST 2015


Hi Stephen,

Looks like a bug, I've only tested with 4096 bit keys.
Probably just MAX_PRIVKEY_SIZE etc needs increasing in
options.h, and some buffer sizes in keyimport.c

Where did a 8192 bit key come from, out of interest?

CHeers,
Matt

On Sun, Feb 08, 2015 at 09:08:17PM -0800, Stephen Kent wrote:
> dropbearconvert seems to crash on large RSA key sizes (the host key
> I'm trying to convert is 8192 bits):
> 
> $ openssl rsa -text -noout -in /etc/ssh/ssh_host_rsa_key 2>/dev/null | head -n 1
> Private-Key: (8196 bit)
> $ dropbearconvert openssh dropbear "/etc/ssh/ssh_host_rsa_key"
> "./dropbear_rsa_host_key"
> Exited: Bad buf_getwriteptr
> 
> dropbearconvert works fine on OpenSSH's default 2048-bit RSA host key.
> 
> Is this a bug? If so, is this the proper place to report it or is
> there another procedure I should follow?
> 
> (Please CC me on replies as I am not on this list.)
> 
> Thanks,
> 
> Stephen


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