postgresql/contrib/test_decoding
Tom Lane 6a3d3965d6 Fix core dump in ReorderBufferRestoreChange on alignment-picky platforms.
When re-reading an update involving both an old tuple and a new tuple from
disk, reorderbuffer.c was careless about whether the new tuple is suitably
aligned for direct access --- in general, it isn't.  We'd missed seeing
this in the buildfarm because the contrib/test_decoding tests exercise this
code path only a few times, and by chance all of those cases have old
tuples with length a multiple of 4, which is usually enough to make the
access to the new tuple's t_len safe.  For some still-not-entirely-clear
reason, however, Debian's sparc build gets a bus error, as reported by
Christoph Berg; perhaps it's assuming 8-byte alignment of the pointer?

The lack of previous field reports is probably because you need all of
these conditions to trigger a crash: an alignment-picky platform (not
Intel), a transaction large enough to spill to disk, an update within
that xact that changes a primary-key field and has an odd-length old tuple,
and of course logical decoding tracing the transaction.

Avoid the alignment assumption by using memcpy instead of fetching t_len
directly, and add a test case that exposes the crash on picky platforms.
Back-patch to 9.4 where the bug was introduced.

Discussion: <20160413094117.GC21485@msg.credativ.de>
2016-04-14 19:42:21 -04:00
..
expected Fix core dump in ReorderBufferRestoreChange on alignment-picky platforms. 2016-04-14 19:42:21 -04:00
specs Force synchronous_commit=on in test_decoding's concurrent_ddl_dml.spec. 2016-03-03 17:22:25 -08:00
sql Fix core dump in ReorderBufferRestoreChange on alignment-picky platforms. 2016-04-14 19:42:21 -04:00
.gitignore
logical.conf
Makefile Generic Messages for Logical Decoding 2016-04-06 10:05:41 +01:00
test_decoding.c Generic Messages for Logical Decoding 2016-04-06 10:05:41 +01:00