On Thu, Mar 23, 2017 at 5:15 PM, Michael Paquier <michael.paqu...@gmail.com> wrote: > On Tue, Mar 21, 2017 at 10:57 PM, Aleksander Alekseev > <a.aleks...@postgrespro.ru> wrote: >> Recently I've decided to run PostgreSQL under Valgrind according to wiki >> description [1]. Lots of warnings are generated [2] but it is my >> understanding that all of them are false-positive. For instance I've >> found these two reports particularly interesting: >> >> ``` >> ==00:00:40:40.161 7677== Use of uninitialised value of size 8 >> ==00:00:40:40.161 7677== at 0xA15FF5: pg_b64_encode (base64.c:68) >> ==00:00:40:40.161 7677== by 0x6FFE85: scram_build_verifier >> (auth-scram.c:348) >> ==00:00:40:40.161 7677== by 0x6F3F76: encrypt_password (crypt.c:171) >> ==00:00:40:40.161 7677== by 0x68F40C: CreateRole (user.c:403) >> ==00:00:40:40.161 7677== by 0x85D53A: standard_ProcessUtility >> (utility.c:716) >> ==00:00:40:40.161 7677== by 0x85CCC7: ProcessUtility (utility.c:353) >> ==00:00:40:40.161 7677== by 0x85BD22: PortalRunUtility (pquery.c:1165) >> ==00:00:40:40.161 7677== by 0x85BF20: PortalRunMulti (pquery.c:1308) >> ==00:00:40:40.161 7677== by 0x85B4A0: PortalRun (pquery.c:788) >> ==00:00:40:40.161 7677== by 0x855672: exec_simple_query (postgres.c:1101) >> ==00:00:40:40.161 7677== by 0x8597BB: PostgresMain (postgres.c:4066) >> ==00:00:40:40.161 7677== by 0x7C6322: BackendRun (postmaster.c:4317) >> ==00:00:40:40.161 7677== Uninitialised value was created by a stack >> allocation >> ==00:00:40:40.161 7677== at 0x6FFDB7: scram_build_verifier >> (auth-scram.c:328) > > I can see those warnings as well after calling a code path of > scram_build_verifier(), and I have a hard time seeing that as nothing > else than a false positive as you do. All those warnings go away if > you just initialize just do MemSet(salt, 0, SCRAM_SALT_LEN) before > calling pg_backend_random() but this data is filled in with > RAND_bytes() afterwards (if built with openssl). The estimated lengths > of the encoding are also correct. I don't see immediately what's wrong > here, this deserves a second look...
And it seems to me that this is caused by the routines of OpenSSL. When building without --with-openssl, using the fallback implementations of SHA256 and RAND_bytes I see no warnings generated by scram_build_verifier... I think it makes most sense to discard that from the list of open items. -- Michael -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
