Bug 231

Summary: ssh-keygen has fatal error while updating comment in RSA1 key
Product: Portable OpenSSH Reporter: rusr
Component: ssh-keygenAssignee: OpenSSH Bugzilla mailing list <openssh-bugs>
Status: CLOSED FIXED    
Severity: normal    
Priority: P2    
Version: -current   
Hardware: HPPA   
OS: HP-UX   

Description rusr 2002-05-02 06:05:35 AEST 
ssh-keygen reports a fatal error while trying to update the comment field of
an RSA1 key. The error reported is 
"Couldn't obtain random bytes (error 604389476)"

This happens because somewhere between 3.0.2p1 and 3.1p1 (the two versions I 
examined), the calls to the init_rng() and seed_rng() in the main function got 
moved from near the beginning of the function to after where all the options 
are processed. The function do_change_comment() handles the comment changing 
and is called during option processing. do_change_comment() calls a function 
save the key file, which uses the random number generator, which has not been 
initialized or seeded and therefore the random number generator reports an 
error.

The simplest fix, in my opinion, is to move the calls to init_rng() and seed_rng
() back to the beginning of the main function so the random number generator is 
always ready to be used. Since this program is not often called, the 
performance impact is negligible.
Comment 1 Kevin Steves 2002-05-12 05:31:23 AEST 
the error is not seen in current i believe due to the fix to arc4random()
to call seed_rng() correctly.

is there a way we can reduce the diff in terms of moving function calls
around due to delaying RNG seeding?

http://www.eviladmin.org/cgi-bin/cvsweb.cgi/ssh-keygen.c.diff?r1=1.87&r2=1.88
http://www.eviladmin.org/cgi-bin/cvsweb.cgi/ssh-keygen.c.diff?r1=1.91&r2=1.92
Comment 2 Damien Miller 2002-05-13 11:04:58 AEST 
We can just put the call to seed_rng() above all the actions. That is safe and
"future-proof" at the cost of some extraneous processing for some options which
don't need it.

Alternately we can just move the chance comment call to below the seed_rng call
Comment 3 Kevin Steves 2002-07-21 05:05:50 AEST 
fixed:
 - (stevesk) [ssh-keygen.c] bug #231: always init/seed_rng().
Comment 4 Damien Miller 2004-04-14 12:24:18 AEST 
Mass change of RESOLVED bugs to CLOSED