I just now noted the remark above suggesting the remedy to programs which crash abort when having a string parsing error is to not feed it strings it doesn't like. I suppose, mutatis mutandis, were the string one 99 of 100 leave defaulted it could be overlooked. However does anyone really think the string configuring the allowed ciphers isn't tweaked every few months in any serious deployment?
-- 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: Triaged 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 -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
