touch-packages team mailing list archive

[Oleg Strikov <oleg.strikov@xxxxxxxxxxxxx>]

Ryan: Many thanks for providing us with the whole picture!

Just to clarify things.
I *do* think that handling this issue is important.
That's bad when one of the services doesn't start w/o putting some hints to the log.
I just don't think that this is SRU type of issue.
Regular precise/trusty users won't meet this upgrading issue because they use *only* libgnutls-based slapd and their config contains correct cipher-suite information.

I'd be happy to fix this issue in development release but we have nothing to fix there.
Repro case provided in the bug works nicely on vivid and doesn't lead to a crash.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to openldap in Ubuntu.
https://bugs.launchpad.net/bugs/1103353

Title:
  Invalid GnuTLS cipher suite strings causes libldap to crash

Status in openldap package in Ubuntu:
  Fix Released
Status in openldap source package in Precise:
  Won't Fix
Status in openldap source package in Trusty:
  Won't Fix
Status in openldap package in Debian:
  Fix Released

Bug description:
  If the cipher suite string is unacceptable to GnuTLS, libldap_r-2.4
  crashes due to a double free. GnuTLS is extremely picky about the
  cipher suite strings it accepts; as a first measure, try LDAP cipher
  suite string "SECURE256" or "NORMAL". If that stops the crash, then
  you have encountered this bug.

  Typically, the crash report begins with something like

  *** glibc detected *** APPLICATION: double free or corruption (!prev)
  /lib/x86_64-linux-gnu/libc.so.6(+0x7eb96)[0x7fc68cff0b96]
  /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2(+0x38769)[0x7fc68bb13769]
  /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2(+0x3570e)[0x7fc68bb1070e]
  /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2(ldap_pvt_tls_init_def_ctx+0x1d)[0x7fc68bb108ed]
  /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2(+0x35965)[0x7fc68bb10965]
  /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2(+0x35a6d)[0x7fc68bb10a6d]
  /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2(ldap_int_tls_start+0x5d)[0x7fc68bb1149d]

  The actual double free happens in
  openldap/libraries/libldap/tls2.c:ldap_int_tls_init_ctx(), in the
  ldap_pvt_tls_ctx_free(lo->ldo_tls_ctx); call in the error_exit: path.

  The root cause of the double free is lack of GnuTLS return value
  checks when calling gnutls_priority*() functions. The code simply
  assumes they succeed, and when GnuTLS fails to provide a valid context
  due to those failures, ldap_int_tls_init_ctx() tries to free the
  never-fully-initialized context.

  A simple fix is to create GnuTLS security contexts using the
  configured cipher suite string, instead of "NORMAL" as
  openldap/libraries/libldap/tls_g.c now does. If the cipher suite
  string is invalid, then do not create the context at all. This is
  caught earlier in ldap_int_tls_init_ctx(), and avoids the crash.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/openldap/+bug/1103353/+subscriptions