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2011-09-07Fix corner case bug in numeric to_char().Tom Lane
Trailing-zero stripping applied by the FM specifier could strip zeroes to the left of the decimal point, for a format with no digit positions after the decimal point (such as "FM999."). Reported and diagnosed by Marti Raudsepp, though I didn't use his patch.
2011-09-06Avoid possibly accessing off the end of memory in SJIS2004 conversion.Tom Lane
The code in shift_jis_20042euc_jis_2004() would fetch two bytes even when only one remained in the string. Since conversion functions aren't supposed to assume null-terminated input, this poses a small risk of fetching past the end of memory and incurring SIGSEGV. No such crash has been identified in the field, but we've certainly seen the equivalent happen in other code paths, so patch this one all the way back. Report and patch by Noah Misch.
2011-08-26Fix potential memory clobber in tsvector_concat().Tom Lane
tsvector_concat() allocated its result workspace using the "conservative" estimate of the sum of the two input tsvectors' sizes. Unfortunately that wasn't so conservative as all that, because it supposed that the number of pad bytes required could not grow. Which it can, as per test case from Jesper Krogh, if there's a mix of lexemes with positions and lexemes without them in the input data. The fix is to assume that we might add a not-previously-present pad byte for each and every lexeme in the two inputs; which really is conservative, but it doesn't seem worthwhile to try to be more precise. This is an aboriginal bug in tsvector_concat, so back-patch to all versions containing it.
2011-08-16Fix race condition in relcache init file invalidation.Tom Lane
The previous code tried to synchronize by unlinking the init file twice, but that doesn't actually work: it leaves a window wherein a third process could read the already-stale init file but miss the SI messages that would tell it the data is stale. The result would be bizarre failures in catalog accesses, typically "could not read block 0 in file ..." later during startup. Instead, hold RelCacheInitLock across both the unlink and the sending of the SI messages. This is more straightforward, and might even be a bit faster since only one unlink call is needed. This has been wrong since it was put in (in 2002!), so back-patch to all supported releases.
2011-06-17Add overflow checks to int4 and int8 versions of generate_series().Robert Haas
The previous code went into an infinite loop after overflow. In fact, an overflow is not really an error; it just means that the current value is the last one we need to return. So, just arrange to stop immediately when overflow is detected. Back-patch all the way.
2011-05-28Fix null-dereference crash in parse_xml_decl().Tom Lane
parse_xml_decl's header comment says you can pass NULL for any unwanted output parameter, but it failed to honor this contract for the "standalone" flag. The only currently-affected caller is xml_recv, so the net effect is that sending a binary XML value containing a standalone parameter in its xml declaration would crash the backend. Per bug #6044 from Christopher Dillard. In passing, remove useless initializations of parse_xml_decl's output parameters in xml_parse. Back-patch to 8.3, where this code was introduced.
2011-05-26Make decompilation of optimized CASE constructs more robust.Tom Lane
We had some hacks in ruleutils.c to cope with various odd transformations that the optimizer could do on a CASE foo WHEN "CaseTestExpr = RHS" clause. However, the fundamental impossibility of covering all cases was exposed by Heikki, who pointed out that the "=" operator could get replaced by an inlined SQL function, which could contain nearly anything at all. So give up on the hacks and just print the expression as-is if we fail to recognize it as "CaseTestExpr = RHS". (We must cover that case so that decompiled rules print correctly; but we are not under any obligation to make EXPLAIN output be 100% valid SQL in all cases, and already could not do so in some other cases.) This approach requires that we have some printable representation of the CaseTestExpr node type; I used "CASE_TEST_EXPR". Back-patch to all supported branches, since the problem case fails in all.
2011-05-24Avoid uninitialized bits in the result of QTN2QT().Tom Lane
Found with additional valgrind testing. Noah Misch
2011-04-29Remove special case for xmin == xmax in HeapTupleSatisfiesVacuum().Tom Lane
VACUUM was willing to remove a committed-dead tuple immediately if it was deleted by the same transaction that inserted it. The idea is that such a tuple could never have been visible to any other transaction, so we don't need to keep it around to satisfy MVCC snapshots. However, there was already an exception for tuples that are part of an update chain, and this exception created a problem: we might remove TOAST tuples (which are never part of an update chain) while their parent tuple stayed around (if it was part of an update chain). This didn't pose a problem for most things, since the parent tuple is indeed dead: no snapshot will ever consider it visible. But MVCC-safe CLUSTER had a problem, since it will try to copy RECENTLY_DEAD tuples to the new table. It then has to copy their TOAST data too, and would fail if VACUUM had already removed the toast tuples. Easiest fix is to get rid of the special case for xmin == xmax. This may delay reclaiming dead space for a little bit in some cases, but it's by far the most reliable way to fix the issue. Per bug #5998 from Mark Reid. Back-patch to 8.3, which is the oldest version with MVCC-safe CLUSTER.
2011-04-29Rewrite pg_size_pretty() to avoid compiler bug.Tom Lane
Convert it to use successive shifts right instead of increasing a divisor. This is probably a tad more efficient than the original coding, and it's nicer-looking than the previous patch because we don't need a special case to avoid overflow in the last branch. But the real reason to do it is to avoid a Solaris compiler bug, as per results from buildfarm member moa.
2011-04-27Fix array- and path-creating functions to ensure padding bytes are zeroes.Tom Lane
Per recent discussion, it's important for all computed datums (not only the results of input functions) to not contain any ill-defined (uninitialized) bits. Failing to ensure that can result in equal() reporting that semantically indistinguishable Consts are not equal, which in turn leads to bizarre and undesirable planner behavior, such as in a recent example from David Johnston. We might eventually try to fix this in a general manner by allowing datatypes to define identity-testing functions, but for now the path of least resistance is to expect datatypes to force all unused bits into consistent states. Per some testing by Noah Misch, array and path functions seem to be the only ones presenting risks at the moment, so I looked through all the functions in adt/array*.c and geo_ops.c and fixed them as necessary. In the array functions, the easiest/safest fix is to allocate result arrays with palloc0 instead of palloc. Possibly in future someone will want to look into whether we can just zero the padding bytes, but that looks too complex for a back-patchable fix. In the path functions, we already had a precedent in path_in for just zeroing the one known pad field, so duplicate that code as needed. Back-patch to all supported branches.
2011-04-25Fix pg_size_pretty() to avoid overflow for inputs close to INT64_MAX.Tom Lane
The expression that tried to round the value to the nearest TB could overflow, leading to bogus output as reported in bug #5993 from Nicola Cossu. This isn't likely to ever happen in the intended usage of the function (if it could, we'd be needing to use a wider datatype instead); but it's not hard to give the expected output, so let's do so.
2011-03-22Avoid potential deadlock in InitCatCachePhase2().Tom Lane
Opening a catcache's index could require reading from that cache's own catalog, which of course would acquire AccessShareLock on the catalog. So the original coding here risks locking index before heap, which could deadlock against another backend trying to get exclusive locks in the normal order. Because InitCatCachePhase2 is only called when a backend has to start up without a relcache init file, the deadlock was seldom seen in the field. (And by the same token, there's no need to worry about any performance disadvantage; so not much point in trying to distinguish exactly which catalogs have the risk.) Bug report, diagnosis, and patch by Nikhil Sontakke. Additional commentary by me. Back-patch to all supported branches.
2011-03-11On further reflection, we'd better do the same in int.c.Tom Lane
We previously heard of the same problem in int24div(), so there's not a good reason to suppose the problem is confined to cases involving int8.
2011-03-11Put in some more safeguards against executing a division-by-zero.Tom Lane
Add dummy returns before every potential division-by-zero in int8.c, because apparently further "improvements" in gcc's optimizer have enabled it to break functions that weren't broken before. Aurelien Jarno, via Martin Pitt
2011-02-01Fix wrong error reports in 'number of array dimensions exceeds theItagaki Takahiro
maximum allowed' messages, that have reported one-less dimensions. Alexey Klyukin
2011-01-17Fix miscalculation of itemsafter in array_set_slice().Tom Lane
If the slice to be assigned to was before the existing array lower bound (requiring at least one null element to spring into existence to fill the gap), the code miscalculated how many entries needed to be copied from the old array's null bitmap. This could result in trashing the array's data area (as seen in bug #5840 from Karsten Loesing), or worse. This has been broken since we first allowed the behavior of assigning to non-adjacent slices, in 8.2. Back-patch to all affected versions.
2010-12-28Ooops, no DATE_IS_NOBEGIN/DATE_IS_NOEND in 8.3 or 8.2 ...Tom Lane
I heard the siren call of git cherry-pick, but should have lashed myself to the mast.
2010-12-28Avoid unexpected conversion overflow in planner for distant date values.Tom Lane
The "date" type supports a wider range of dates than int64 timestamps do. However, there is pre-int64-timestamp code in the planner that assumes that all date values can be converted to timestamp with impunity. Fortunately, what we really need out of the conversion is always a double (float8) value; so even when the date is out of timestamp's range it's possible to produce a sane answer. All we need is a code path that doesn't try to force the result into int64. Per trouble report from David Rericha. Back-patch to all supported versions. Although this is surely a corner case, there's not much point in advertising a date range wider than timestamp's if we will choke on such values in unexpected places.
2010-12-19Fix up handling of simple-form CASE with constant test expression.Tom Lane
eval_const_expressions() can replace CaseTestExprs with constants when the surrounding CASE's test expression is a constant. This confuses ruleutils.c's heuristic for deparsing simple-form CASEs, leading to Assert failures or "unexpected CASE WHEN clause" errors. I had put in a hack solution for that years ago (see commit 514ce7a331c5bea8e55b106d624e55732a002295 of 2006-10-01), but bug #5794 from Peter Speck shows that that solution failed to cover all cases. Fortunately, there's a much better way, which came to me upon reflecting that Peter's "CASE TRUE WHEN" seemed pretty redundant: we can "simplify" the simple-form CASE to the general form of CASE, by simply omitting the constant test expression from the rebuilt CASE construct. This is intuitively valid because there is no need for the executor to evaluate the test expression at runtime; it will never be referenced, because any CaseTestExprs that would have referenced it are now replaced by constants. This won't save a whole lot of cycles, since evaluating a Const is pretty cheap, but a cycle saved is a cycle earned. In any case it beats kluging ruleutils.c still further. So this patch improves const-simplification and reverts the previous change in ruleutils.c. Back-patch to all supported branches. The bug exists in 8.1 too, but it's out of warranty.
2010-12-19Fix erroneous parsing of tsquery input "... & !(subexpression) | ..."Tom Lane
After parsing a parenthesized subexpression, we must pop all pending ANDs and NOTs off the stack, just like the case for a simple operand. Per bug #5793. Also fix clones of this routine in contrib/intarray and contrib/ltree, where input of types query_int and ltxtquery had the same problem. Back-patch to all supported versions.
2010-12-08Force default wal_sync_method to be fdatasync on Linux.Tom Lane
Recent versions of the Linux system header files cause xlogdefs.h to believe that open_datasync should be the default sync method, whereas formerly fdatasync was the default on Linux. open_datasync is a bad choice, first because it doesn't actually outperform fdatasync (in fact the reverse), and second because we try to use O_DIRECT with it, causing failures on certain filesystems (e.g., ext4 with data=journal option). This part of the patch is largely per a proposal from Marti Raudsepp. More extensive changes are likely to follow in HEAD, but this is as much change as we want to back-patch. Also clean up confusing code and incorrect documentation surrounding the fsync_writethrough option. Those changes shouldn't result in any actual behavioral change, but I chose to back-patch them anyway to keep the branches looking similar in this area. In 9.0 and HEAD, also do some copy-editing on the WAL Reliability documentation section. Back-patch to all supported branches, since any of them might get used on modern Linux versions.
2010-11-10Fix line_construct_pm() for the case of "infinite" (DBL_MAX) slope.Tom Lane
This code was just plain wrong: what you got was not a line through the given point but a line almost indistinguishable from the Y-axis, although not truly vertical. The only caller that tries to use this function with m == DBL_MAX is dist_ps_internal for the case where the lseg is horizontal; it would end up producing the distance from the given point to the place where the lseg's line crosses the Y-axis. That function is used by other operators too, so there are several operators that could compute wrong distances from a line segment to something else. Per bug #5745 from jindiax. Back-patch to all supported branches.
2010-11-02Ensure an index that uses a whole-row Var still depends on its table.Tom Lane
We failed to record any dependency on the underlying table for an index declared like "create index i on t (foo(t.*))". This would create trouble if the table were dropped without previously dropping the index. To fix, simplify some overly-cute code in index_create(), accepting the possibility that sometimes the whole-table dependency will be redundant. Also document this hazard in dependency.c. Per report from Kevin Grittner. In passing, prevent a core dump in pg_get_indexdef() if the index's table can't be found. I came across this while experimenting with Kevin's example. Not sure it's a real issue when the catalogs aren't corrupt, but might as well be cautious. Back-patch to all supported versions.
2010-09-22Convert cvsignore to gitignore, and add .gitignore for build targets.Magnus Hagander
2010-09-02Fix up flushing of composite-type typcache entries to be driven directly byTom Lane
SI invalidation events, rather than indirectly through the relcache. In the previous coding, we had to flush a composite-type typcache entry whenever we discarded the corresponding relcache entry. This caused problems at least when testing with RELCACHE_FORCE_RELEASE, as shown in recent report from Jeff Davis, and might result in real-world problems given the kind of unexpected relcache flush that that test mechanism is intended to model. The new coding decouples relcache and typcache management, which is a good thing anyway from a structural perspective. The cost is that we have to search the typcache linearly to find entries that need to be flushed. There are a couple of ways we could avoid that, but at the moment it's not clear it's worth any extra trouble, because the typcache contains very few entries in typical operation. Back-patch to 8.2, the same as some other recent fixes in this general area. The patch could be carried back to 8.0 with some additional work, but given that it's only hypothetical whether we're fixing any problem observable in the field, it doesn't seem worth the work now.
2010-08-16Arrange to fsync the contents of lockfiles (both postmaster.pid and theTom Lane
socket lockfile) when writing them. The lack of an fsync here may well explain two different reports we've seen of corrupted lockfile contents, which doesn't particularly bother the running server but can prevent a new server from starting if the old one crashes. Per suggestion from Alvaro. Back-patch to all supported versions.
2010-08-13Fix Assert failure in PushOverrideSearchPath when trying to restore a searchTom Lane
path that specifies useTemp, but there is no active temp schema in the current session. (This can happen if the path was saved during a transaction that created a temp schema and was later rolled back.) For existing callers it's sufficient to ignore the useTemp flag in this case, though we might later want to offer an option to create a fresh temp schema. So far as I can tell this is just an Assert failure: in a non-assert build, the code would push a zero onto the new search path, which is useless but not very harmful. Per bug report from Heikki. Back-patch to 8.3; prior versions don't have this code.
2010-08-03Fix core dump in QTNodeCompare when tsquery_cmp() is applied to two emptyTom Lane
tsqueries. CompareTSQ has to have a guard for the case rather than blindly applying QTNodeCompare to random data past the end of the datums. Also, change QTNodeCompare to be a little less trusting: use an actual test rather than just Assert'ing that the input is sane. Problem encountered while investigating another issue (I saw a core dump in autoanalyze on a table containing multiple empty tsquery values). Back-patch to all branches with tsquery support. In HEAD, also fix some bizarre (though not outright wrong) coding in tsq_mcontains().
2010-07-13Oops, in the previous fix to prevent a cursor that's being used in a FORHeikki Linnakangas
loop from being dropped, I missed subtransaction cleanup. Pinned portals must be dropped at subtransaction cleanup just as they are at main transaction cleanup. Per bug #5556 by Robert Walker. Backpatch to 8.0, 7.4 didn't have subtransactions.
2010-07-09Avoid an Assert failure in deconstruct_array() by making get_attstatsslot()Tom Lane
use the actual element type of the array it's disassembling, rather than trusting the type OID passed in by its caller. This is needed because sometimes the planner passes in a type OID that's only binary-compatible with the target column's type, rather than being an exact match. Per an example from Bernd Helmle. Possibly we should refactor get_attstatsslot/free_attstatsslot to not expect the caller to supply type ID data at all, but for now I'll just do the minimum-change fix. Back-patch to 7.4. Bernd's test case only crashes back to 8.0, but since these subroutines are the same in 7.4, I suspect there may be variant cases that would crash 7.4 as well.
2010-07-05The previous fix in CVS HEAD and 8.4 for handling the case where a cursorHeikki Linnakangas
being used in a PL/pgSQL FOR loop is closed was inadequate, as Tom Lane pointed out. The bug affects FOR statement variants too, because you can close an implicitly created cursor too by guessing the "<unnamed portal X>" name created for it. To fix that, "pin" the portal to prevent it from being dropped while it's being used in a PL/pgSQL FOR loop. Backpatch all the way to 7.4 which is the oldest supported version.
2010-05-28Rewrite LIKE's %-followed-by-_ optimization so it really works (this timeTom Lane
for sure ;-)). It now also optimizes more cases, such as %_%_. Improve comments too. Per bug #5478. In passing, also rename the TCHAR macro to GETCHAR, because pgindent is messing with the formatting of the former (apparently it now thinks TCHAR is a typedef name). Back-patch to 8.3, where the bug was introduced.
2010-05-27Change ps_status.c to explicitly track the current logical length of ps_buffer.Tom Lane
This saves cycles in get_ps_display() on many popular platforms, and more importantly ensures that get_ps_display() will correctly return an empty string if init_ps_display() hasn't been called yet. Per trouble report from Ray Stell, in which log_line_prefix %i produced junk early in backend startup. Back-patch to 8.0. 7.4 doesn't have %i and its version of get_ps_display() makes no pretense of avoiding pad junk anyhow.
2010-05-08Work around a subtle portability problem in use of printf %s format.Tom Lane
Depending on which spec you read, field widths and precisions in %s may be counted either in bytes or characters. Our code was assuming bytes, which is wrong at least for glibc's implementation, and in any case libc might have a different idea of the prevailing encoding than we do. Hence, for portable results we must avoid using anything more complex than just "%s" unless the string to be printed is known to be all-ASCII. This patch fixes the cases I could find, including the psql formatting failure reported by Hernan Gonzalez. In HEAD only, I also added comments to some places where it appears safe to continue using "%.*s".
2010-04-14Fix a problem introduced by my patch of 2010-01-12 that revised the wayTom Lane
relcache reload works. In the patched code, a relcache entry in process of being rebuilt doesn't get unhooked from the relcache hash table; which means that if a cache flush occurs due to sinval queue overrun while we're rebuilding it, the entry could get blown away by RelationCacheInvalidate, resulting in crash or misbehavior. Fix by ensuring that an entry being rebuilt has positive refcount, so it won't be seen as a target for removal if a cache flush occurs. (This will mean that the entry gets rebuilt twice in such a scenario, but that's okay.) It appears that the problem can only arise within a transaction that has previously reassigned the relfilenode of a pre-existing table, via TRUNCATE or a similar operation. Per bug #5412 from Rusty Conover. Back-patch to 8.2, same as the patch that introduced the problem. I think that the failure can't actually occur in 8.2, since it lacks the rd_newRelfilenodeSubid optimization, but let's make it work like the later branches anyway. Patch by Heikki, slightly editorialized on by me.
2010-03-25Prevent ALTER USER f RESET ALL from removing the settings that were put thereAlvaro Herrera
by a superuser -- "ALTER USER f RESET setting" already disallows removing such a setting. Apply the same treatment to ALTER DATABASE d RESET ALL when run by a database owner that's not superuser.
2010-03-03Export xml.c's libxml-error-handling support so that contrib/xml2 can use itTom Lane
too, instead of duplicating the functionality (badly). I renamed xml_init to pg_xml_init, because the former seemed just a bit too generic to be safe as a global symbol. I considered likewise renaming xml_ereport to pg_xml_ereport, but felt that the reference to ereport probably made it sufficiently PG-centric already.
2010-03-03pgindent run on xml.c in 8.3 branch, per request from Tom.Bruce Momjian
2010-03-01Back-patch changes of 2009-05-13 in xml.c's memory management.Tom Lane
I was afraid to do this when these changes were first made, but now that 8.4 has seen some field use it should be all right to back-patch. These changes are really quite necessary in order to give xml.c any hope of co-existing with loadable modules that also wish to use libxml2.
2010-02-25Add configuration parameter ssl_renegotiation_limit to controlMagnus Hagander
how often we do SSL session key renegotiation. Can be set to 0 to disable renegotiation completely, which is required if a broken SSL library is used (broken patches to CVE-2009-3555 a known cause) or when using a client library that can't do renegotiation.
2010-01-24Fix assorted core dumps and Assert failures that could occur duringTom Lane
AbortTransaction or AbortSubTransaction, when trying to clean up after an error that prevented (sub)transaction start from completing: * access to TopTransactionResourceOwner that might not exist * assert failure in AtEOXact_GUC, if AtStart_GUC not called yet * assert failure or core dump in AfterTriggerEndSubXact, if AfterTriggerBeginSubXact not called yet Per testing by injecting elog(ERROR) at successive steps in StartTransaction and StartSubTransaction. It's not clear whether all of these cases could really occur in the field, but at least one of them is easily exposed by simple stress testing, as per my accidental discovery yesterday.
2010-01-23Insert CHECK_FOR_INTERRUPTS calls into loops in dbsize.c, to ensure thatTom Lane
the various disk-size-reporting functions will respond to query cancel reasonably promptly even in very large databases. Per report from Kevin Grittner.
2010-01-18Fix portalmem.c to avoid keeping a dangling pointer to a cached plan listTom Lane
after it's released its reference count for the cached plan. There are code paths that might try to examine the plan list before noticing that the portal is already in aborted state. Report and diagnosis by Tatsuo Ishii, though this isn't exactly his proposed patch.
2010-01-13When loading critical system indexes into the relcache, ensure we lock theTom Lane
underlying catalog not only the index itself. Otherwise, if the cache load process touches the catalog (which will happen for many though not all of these indexes), we are locking index before parent table, which can result in a deadlock against processes that are trying to lock them in the normal order. Per today's failure on buildfarm member gothic_moth; it's surprising the problem hadn't been identified before. Back-patch to 8.2. Earlier releases didn't have the issue because they didn't try to lock these indexes during load (instead assuming that they couldn't change schema at all during multiuser operation).
2010-01-12Fix relcache reload mechanism to be more robust in the face of errorsTom Lane
occurring during a reload, such as query-cancel. Instead of zeroing out an existing relcache entry and rebuilding it in place, build a new relcache entry, then swap its contents with the old one, then free the new entry. This avoids problems with code believing that a previously obtained pointer to a cache entry must still reference a valid entry, as seen in recent failures on buildfarm member jaguar. (jaguar is using CLOBBER_CACHE_ALWAYS which raises the probability of failure substantially, but the problem could occur in the field without that.) The previous design was okay when it was made, but subtransactions and the ResourceOwner mechanism make it unsafe now. Also, make more use of the already existing rd_isvalid flag, so that we remember that the entry requires rebuilding even if the first attempt fails. Back-patch as far as 8.2. Prior versions have enough issues around relcache reload anyway (due to inadequate locking) that fixing this one doesn't seem worthwhile.
2010-01-07Make bit/varbit substring() treat any negative length as meaning "all the restTom Lane
of the string". The previous coding treated only -1 that way, and would produce an invalid result value for other negative values. We ought to fix it so that 2-parameter bit substring() is a different C function and the 3-parameter form throws error for negative length, but that takes a pg_proc change which is impractical in the back branches; and in any case somebody might be relying on -1 working this way. So just do this as a back-patchable fix.
2009-12-29Previous fix for temporary file management broke returning a set fromHeikki Linnakangas
PL/pgSQL function within an exception handler. Make sure we use the right resource owner when we create the tuplestore to hold returned tuples. Simplify tuplestore API so that the caller doesn't need to be in the right memory context when calling tuplestore_put* functions. tuplestore.c automatically switches to the memory context used when the tuplestore was created. Tuplesort was already modified like this earlier. This patch also removes the now useless MemoryContextSwitch calls from callers. Report by Aleksei on pgsql-bugs on Dec 22 2009. Backpatch to 8.1, like the previous patch that broke this.
2009-12-12Fix integer-to-bit-string conversions to handle the first fractional byteTom Lane
correctly when the output bit width is wider than the given integer by something other than a multiple of 8 bits. This has been wrong since I first wrote that code for 8.0 :-(. Kudos to Roman Kononov for being the first to notice, though I didn't use his patch. Per bug #5237.
2009-12-09Prevent indirect security attacks via changing session-local state withinTom Lane
an allegedly immutable index function. It was previously recognized that we had to prevent such a function from executing SET/RESET ROLE/SESSION AUTHORIZATION, or it could trivially obtain the privileges of the session user. However, since there is in general no privilege checking for changes of session-local state, it is also possible for such a function to change settings in a way that might subvert later operations in the same session. Examples include changing search_path to cause an unexpected function to be called, or replacing an existing prepared statement with another one that will execute a function of the attacker's choosing. The present patch secures VACUUM, ANALYZE, and CREATE INDEX/REINDEX against these threats, which are the same places previously deemed to need protection against the SET ROLE issue. GUC changes are still allowed, since there are many useful cases for that, but we prevent security problems by forcing a rollback of any GUC change after completing the operation. Other cases are handled by throwing an error if any change is attempted; these include temp table creation, closing a cursor, and creating or deleting a prepared statement. (In 7.4, the infrastructure to roll back GUC changes doesn't exist, so we settle for rejecting changes of "search_path" in these contexts.) Original report and patch by Gurjeet Singh, additional analysis by Tom Lane. Security: CVE-2009-4136