(ITS#5361) cert verification failures with GnuTLS and DNS subjectAltName

Joe Orton joe at manyfish.co.uk
Thu Feb 14 23:34:50 CET 2008

On Sun, Feb 10, 2008 at 01:58:37AM -0800, Howard Chu wrote:
> Yes. I've just tested with GnuTLS 2.2.1 and 2.3.0 and see the same result 
> you're seeing. The change is here:
> http://git.savannah.gnu.org/gitweb/?p=gnutls.git;a=commitdiff;h=deaa3ac31c2e83c292562ab66c1817c7ebc27048
> and it is clearly a bug, since subjectAltName's are not necessarily 
> strings. (E.g., they can also be IP addresses, which are just 4 or 16 
> octets.) If you notice in the diff, they set
> 	 *name_size = len + 1;
> and then later
> 	name[len] = 0;
> but this occurs *after* the check for SHORT_MEMORY_BUFFER. So in fact they 
> can cause a write past the end of the supplied buffer.
> This patch should be reverted, it is clearly wrong.

FWIW, I agree.  neon's test cases for subjectAltName support are 
breaking with 2.3.0 as well.  Reverting the changeset Howard referenced 
fixes the issues.


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