[krbdev.mit.edu #9101] git commit

[Greg Hudson via RT]

Mon Aug 07 17:54:44 2023: Request 9101 was acted upon.
 Transaction: Ticket created by ghudson at mit.edu
       Queue: krb5
     Subject: git commit
       Owner: ghudson at mit.edu
  Requestors: 
      Status: new
 Ticket <URL: https://krbdev.mit.edu/rt/Ticket/Display.html?id=9101 >



Fix double-free in KDC TGS processing

When issuing a ticket for a TGS renew or validate request, copy only
the server field from the outer part of the header ticket to the new
ticket.  Copying the whole structure causes the enc_part pointer to be
aliased to the header ticket until krb5_encrypt_tkt_part() is called,
resulting in a double-free if handle_authdata() fails.

[ghudson at mit.edu: changed the fix to avoid aliasing enc_part rather
than check for aliasing before freeing; rewrote commit message]

CVE-2023-39975:

In MIT krb5 release 1.21, an authenticated attacker can cause a KDC to
free the same pointer twice if it can induce a failure in
authorization data handling.

https://github.com/krb5/krb5/commit/88a1701b423c13991a8064feeb26952d3641d840
Author: Andreas Schneider <asn at samba.org>
Committer: Greg Hudson <ghudson at mit.edu>
Commit: 88a1701b423c13991a8064feeb26952d3641d840
Branch: master
 src/kdc/do_tgs_req.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)