Re: bin/51267 (NETBSD 3.1 crashes on continuous ping)

["Greg A. Woods" <woods%planix.ca@localhost>]

The following reply was made to PR bin/51267; it has been noted by GNATS.

From: "Greg A. Woods" <woods%planix.ca@localhost>
To: NetBSD GNATS <gnats-bugs%NetBSD.org@localhost>
Cc: 
Subject: Re: bin/51267 (NETBSD 3.1 crashes on continuous ping)
Date: Thu, 30 Jun 2016 13:32:17 -0700

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 Turns out this is almost certainly due to the signal handlers in ping
 calling non-reentrant functions (stdio, and malloc via stdio).
 
 See the related question, which has been updated with additional
 information, along with my answer here:
 
   http://stackoverflow.com/a/38131441/816536
 
 
 A good quick mostly fix would be to import OpenBSD's ping (and to keep
 in mind tracking it as it appears they will end up with a merged
 ping/ping6 at some point (soon?)).
 
 I say "mostly" because it appears on quick inspection that rev. 1.139 of
 OpenBSD ping still has a call to summary(signo) in a signal handler, and
 though their summary() avoids malloc() and stdout if called from a
 signal handler, I think on first glance it may still not be 100%
 reentrant due to the libc calls it does still make.  It's still 110%
 better than what we have in NetBSD now though.  (I think I've seen a
 crash from a signal handler calling NetBSD's snprintf(), but I'm not
 completely sure my memory is correct about that, and I have no notes
 about it that I can find.)
 
 The OpenBSD ping could have the SIGCONT feature patched into it, but
 that's hardly a critical feature that would go missing.
 
 BTW, this probably isn't a security-critical fix given that ping drops
 privs before setting up signal handlers, and I don't think it opens any
 avenues for remote exploitation.
 
 --=20
 						Greg A. Woods
 						Planix, Inc.
 
 <woods%planix.com@localhost>       +1 250 762-7675        http://www.planix.com/
 
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