Coverity complained that we weren't doing that, and it's right.
This fix just makes fmtIdEnc() honor the general convention that OOM
causes a PQExpBuffer to become marked "broken", without any immediate
error. In the pretty-unlikely case that we actually did hit OOM here,
the end result would be to return an empty string to the caller,
probably resulting in invalid SQL syntax in an issued command (if
nothing else went wrong, which is even more unlikely). It's tempting
to throw an "out of memory" error if the buffer becomes broken, but
there's not a lot of point in doing that only here and not in hundreds
of other PQExpBuffer-using places in pg_dump and similar callers.
The whole issue could do with some non-time-crunched redesign, perhaps.
This is a followup to the fixes for CVE-2025-1094, and should be
included if cherry-picking those fixes.
Instead of dropping the trailing byte(s) of an invalid or incomplete
multibyte character, replace only the first byte with a known-invalid
sequence, and process the rest normally. This seems less likely to
confuse incautious callers than the behavior adopted in 5dc1e42b4.
While we're at it, adjust PQescapeStringInternal to produce at most
one bleat about invalid multibyte characters per string. This
matches the behavior of PQescapeInternal, and avoids the risk of
producing tons of repetitive junk if a long string is simply given
in the wrong encoding.
This is a followup to the fixes for CVE-2025-1094, and should be
included if cherry-picking those fixes.
Author: Andres Freund <andres@anarazel.de>
Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us>
Reported-by: Jeff Davis <pgsql@j-davis.com>
Discussion: https://postgr.es/m/20250215012712.45@rfd.leadboat.com
Backpatch-through: 13
In 5dc1e42b4f I fixed bugs in various escape functions, unfortunately as part
of that I introduced a new bug in PQescapeLiteral()/PQescapeIdentifier(). The
bug is that I made PQescapeInternal() just use strlen(), rather than taking
the specified input length into account.
That's bad, because it can lead to including input that wasn't intended to be
included (in case len is shorter than null termination of the string) and
because it can lead to reading invalid memory if the input string is not null
terminated.
Expand test_escape to this kind of bug:
a) for escape functions with length support, append data that should not be
escaped and check that it is not
b) add valgrind requests to detect access of bytes that should not be touched
Author: Tom Lane <tgl@sss.pgh.pa.us>
Author: Andres Freund <andres@anarazel.de
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/Z64jD3u46gObCo1p@pryzbyj2023
Backpatch: 13
Commit 27cc7cd2bc accidentally placed the assertion ensuring
that the pointer isn't NULL after it had already been accessed.
Fix by moving the pointer dereferencing to after the assertion.
Backpatch to all supported branches.
Author: Dmitry Koval <d.koval@postgrespro.ru>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/1618848d-cdc7-414b-9c03-08cf4bef4408@postgrespro.ru
Backpatch-through: 13
When an UPDATE trigger referencing a new table and a DELETE trigger
referencing an old table are both present, MakeTransitionCaptureState()
returns an inconsistent result for UPDATE commands in its set of flags
and tuplestores holding the TransitionCaptureState for transition
tables.
As proved by the test added here, this issue causes a crash in v14 and
earlier versions (down to 11, actually, older versions do not support
triggers on partitioned tables) during cross-partition updates on a
partitioned table. v15 and newer versions are safe thanks to
7103ebb7aa.
This commit fixes the function so that it returns a consistent state
by using portions of the changes made in commit 7103ebb7aa for v13 and
v14. v15 and newer versions are slightly tweaked to match with the
older versions, mainly for consistency across branches.
Author: Kyotaro Horiguchi
Discussion: https://postgr.es/m/20250207.150238.968446820828052276.horikyota.ntt@gmail.com
Backpatch-through: 13
We need to tell fmtId() what encoding to assume, but this function
doesn't know that. Fortunately we can fix that without changing the
function's API, because we can just use SQL_ASCII. That's because
database names in connection requests are effectively binary not text:
no encoding-aware processing will happen on them.
This fixes XversionUpgrade failures seen in the buildfarm. The
alternative of having pg_upgrade use setFmtEncoding() is unappetizing,
given that it's connecting to multiple databases that may have
different encodings.
Andres Freund, Noah Misch, Tom Lane
Security: CVE-2025-1094
On machines where char is unsigned this could lead to option parsing looping
endlessly. It's also too narrow a type on other hardware.
Found via Tom Lane's monitoring of the buildfarm.
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Security: CVE-2025-1094
Backpatch-through: 13
As highlighted by the prior commit, writing correct escape functions is less
trivial than one might hope.
This test module tries to verify that different escaping functions behave
reasonably. It e.g. tests:
- Invalidly encoded input to an escape function leads to invalidly encoded
output
- Trailing incomplete multi-byte characters are handled sensibly
- Escaped strings are parsed as single statement by psql's parser (which
derives from the backend parser)
There are further tests that would be good to add. But even in the current
state it was rather useful for writing the fix in the prior commit.
Reviewed-by: Noah Misch <noah@leadboat.com>
Backpatch-through: 13
Security: CVE-2025-1094
Previously invalidly encoded input to various escaping functions could lead to
the escaped string getting incorrectly parsed by psql. To be safe, escaping
functions need to ensure that neither invalid nor incomplete multi-byte
characters can be used to "escape" from being quoted.
Functions which can report errors now return an error in more cases than
before. Functions that cannot report errors now replace invalid input bytes
with a byte sequence that cannot be used to escape the quotes and that is
guaranteed to error out when a query is sent to the server.
The following functions are fixed by this commit:
- PQescapeLiteral()
- PQescapeIdentifier()
- PQescapeString()
- PQescapeStringConn()
- fmtId()
- appendStringLiteral()
Reported-by: Stephen Fewer <stephen_fewer@rapid7.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Backpatch-through: 13
Security: CVE-2025-1094
This commit adds fmtIdEnc() and fmtQualifiedIdEnc(), which allow to specify
the encoding as an explicit argument. Additionally setFmtEncoding() is
provided, which defines the encoding when no explicit encoding is provided, to
avoid breaking all code using fmtId().
All users of fmtId()/fmtQualifiedId() are either converted to the explicit
version or a call to setFmtEncoding() has been added.
This commit does not yet utilize the now well-defined encoding, that will
happen in a subsequent commit.
Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Backpatch-through: 13
Security: CVE-2025-1094
There are cases where we cannot / do not want to error out for invalidly
encoded input. In such cases it can be useful to replace e.g. an incomplete
multi-byte characters with bytes that will trigger an error when getting
validated as part of a larger string.
Unfortunately, until now, for some encoding no such sequence existed. For
those encodings this commit removes one previously accepted input combination
- we consider that to be ok, as the chosen bytes are outside of the valid
ranges for the encodings, we just previously failed to detect that.
As we cannot add a new field to pg_wchar_table without breaking ABI, this is
implemented "in-line" in the newly added function.
Author: Noah Misch <noah@leadboat.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Backpatch-through: 13
Security: CVE-2025-1094
Commit af35fe501 caused "pgbench -i" to emit a '\r' character
for each data row loaded (when stderr is a terminal).
That's effectively invisible on-screen, but it causes the
connected terminal program to consume a lot of cycles.
It's even worse if you're connected over ssh, as the data
then has to pass through the ssh tunnel.
Simplest fix is to move the added logic inside the if-tests
that check whether to print a progress line. We could do
it another way that avoids duplicating these few lines,
but on the whole this seems the most transparent way to
write it.
Like the previous commit, back-patch to all supported versions.
Reported-by: Andres Freund <andres@anarazel.de>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/4k4drkh7bcmdezq6zbkhp25mnrzpswqi2o75d5uv2eeg3aq6q7@b7kqdmzzwzgb
Backpatch-through: 13
Try to make it absolutely plain that we don't retain the
originally specified time zone, only the UTC timestamp.
While at it, make glossary entries for "UTC" and "GMT".
Author: Robert Treat <rob@xzilla.net>
Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/173796426022.1064.9135167366862649513@wrigleys.postgresql.org
Backpatch-through: 13
Before OpenSSL 1.1.0 the legacy names ssleay32 and libeay32 were
still used on Windows, and while we have support for this auto-
conf the meson buildsystem only used the new names on all plat-
forms. This adds support for the old name scheme when building
on Windows.
This patch only applies to 17 and 16 as master no longer support
OpenSSL 1.0.2.
Author: Darek Ślusarczyk <dslusarczyk@splunk.com>
Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CAN55FZ1Nk8wqY=mTrN78H026TuGV50h2H6uq1PwxhTauPYi3ug@mail.gmail.com
Backpatch-through: 16
Two links in the isn module documentation were pointing to tools
which had been moved, resulting in 404 error responses. Update
to the new URLs for the tools. The link to the Sequoia 2000 page
in the history section was no longer working, and since the page
is no longer available online update our link to point at the
paper instead which is on a stable URL.
These links exist in all versions of the documentation so backpatch
to all supported branches.
Author: Daniel Gustafsson <daniel@yesql.se>
Reported-by: charukiewicz@protonmail.com
Discussion: https://postgr.es/m/173679670185.705.8565555804465055355@wrigleys.postgresql.org
Backpatch-through: 13
Meson 1.7 stopped building all the dependencies of tests as part of the
default build target. But it does breaks CI because we only built the default
target before running the test, and ran the tests with --no-rebuild.
The simplest fix would be to remove --no-rebuild from MTEST_ARGS, but it seems
better to explicitly build the test dependencies, so compiler warnings /
errors are visible as part of the build step.
Discussion: https://postgr.es/m/CAGECzQSvM3iSDmjF+=Kof5an6jN8UbkP_4cKKT9w6GZavmb5yQ@mail.gmail.com
Backpatch: 16-, where meson was added
The missing dependency was, e.g., visible when doing
ninja clean && ninja meson-test-prereq && meson test --no-rebuild --suite setup --suite libpq
This is a bit more complicated than other related fixes, because until now
libpq's tests depended on 'frontend_code', which includes a dependency on
fe_utils, which in turns on libpq. That in turn required
src/interfaces/libpq/test to be entered from the top-level, not from
libpq/meson.build. Because of that the test definitions in libpq/meson.build
could not declare a dependency on the binaries defined in
libpq/test/meson.build.
To fix this, this commit creates frontend_no_fe_utils_code, which allows us to
recurse into libpq/test from withing libpq/meson.build.
Apply this to all branches with meson support, as part of an effort to fix
incorrect test dependencies that can lead to test failures.
Discussion: https://postgr.es/m/CAGECzQSvM3iSDmjF+=Kof5an6jN8UbkP_4cKKT9w6GZavmb5yQ@mail.gmail.com
Discussion: https://postgr.es/m/bdba588f-69a9-4f3e-9b95-62d07210a32e@eisentraut.org
Backpatch: 16-, where meson support was added
The missing dependency was, e.g., visible when doing
ninja clean && ninja meson-test-prereq && meson test --no-rebuild --suite setup --suite cube
because meson (and thus its internal meson-test-prereq target) did not know
about a lot of the required targets.
Previously tmp_install did not actually depend on the relevant files being
built. That was mostly not visible, because "meson test" currently uses the
'default' targets as a test's dependency if no dependency is specified.
However, there are plans to narrow that on the meson side, to make it quicker
to run tests.
Apply this to all branches with meson support, as part of an effort to fix
incorrect test dependencies that can lead to test failures.
Discussion: https://postgr.es/m/CAGECzQSvM3iSDmjF+=Kof5an6jN8UbkP_4cKKT9w6GZavmb5yQ@mail.gmail.com
Discussion: https://postgr.es/m/bdba588f-69a9-4f3e-9b95-62d07210a32e@eisentraut.org
Backpatch: 16-, where meson support was added
Protect against malformed timestamps. Also protect against negative WalSegSz
as it triggers division by zero:
((0x100000000UL) / (WalSegSz)) can turn into zero in
XLogFileName(xlogfilename, ControlFile->checkPointCopy.ThisTimeLineID,
segno, WalSegSz);
because if WalSegSz is -1 then by arithmetic rules in C we get
0x100000000UL / 0xFFFFFFFFFFFFFFFFUL == 0.
Author: Ilyasov Ian <ianilyasov@outlook.com>
Author: Anton Voloshin <a.voloshin@postgrespro.ru>
Backpatch-through: 13
A few of the version checks in vacuum_one_database() do not call
PQfinish() before exiting. This precedent was unintentionally
established in commit 00d1e88d36, and while it's probably not too
problematic, it seems better to properly close the connection.
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/Z6JAwqN1I8ljTuXp%40nathan
Backpatch-through: 13
logging_collector was only mentioning stderr and csvlog, and forgot
about jsonlog. Oversight in dc686681e0, that has added support for
jsonlog in log_destination.
While on it, the description in the GUC table is tweaked to be more
consistent with the documentation and postgresql.conf.sample.
Author: Umar Hayat
Reviewed-by: Ashutosh Bapat, Tom Lane
Discussion: https://postgr.es/m/CAD68Dp1K_vBYqBEukHw=1jF7e76t8aszGZTFL2ugi=H7r=a7MA@mail.gmail.com
Backpatch-through: 13
smgrDoPendingSyncs had two distinct risks of integer overflow while
deciding which way to ensure durability of a newly-created relation.
First, it accumulated the total size of all forks in a variable of
type BlockNumber (uint32). While we restrict an individual fork's
size to fit in that, I don't believe there's such a restriction on
all of them added together. Second, it proceeded to multiply the
sum by BLCKSZ, which most certainly could overflow a uint32.
(The exact expression is total_blocks * BLCKSZ / 1024. The
compiler might choose to optimize that to total_blocks * 8,
which is not at quite as much risk of overflow as a literal
reading would be, but it's still wrong.)
If an overflow did occur it could lead to a poor choice to
shove a very large relation into WAL instead of fsync'ing it.
This wouldn't be fatal, but it could be inefficient.
Change total_blocks to uint64 which should be plenty, and
rearrange the comparison calculation to be overflow-safe.
I noticed this while looking for ramifications of the proposed
change in MAX_KILOBYTES. It's not entirely clear to me why
wal_skip_threshold is limited to MAX_KILOBYTES in the
first place, but in any case this code is unsafe regardless
of the range of wal_skip_threshold.
Oversight in c6b92041d which introduced wal_skip_threshold,
so back-patch to v13.
Discussion: https://postgr.es/m/1a01f0-66ec2d80-3b-68487680@27595217
Backpatch-through: 13
If a column is omitted in an INSERT, and there's no column default,
the code in preptlist.c generates a NULL Const to be inserted.
Furthermore, if the column is of a domain type, we wrap the Const
in CoerceToDomain, so as to throw a run-time error if the domain
has a NOT NULL constraint. That's fine as far as it goes, but
there are two problems:
1. We're being sloppy about the type/typmod that the Const is
labeled with. It really should have the domain's base type/typmod,
since it's the input to CoerceToDomain not the output. This can
result in coerce_to_domain inserting a useless length-coercion
function (useless because it's being applied to a null). The
coercion would typically get const-folded away later, but it'd
be better not to create it in the first place.
2. We're not applying expression preprocessing (specifically,
eval_const_expressions) to the resulting expression tree.
The planner's primary expression-preprocessing pass already happened,
so that means the length coercion step and CoerceToDomain node miss
preprocessing altogether.
This is at the least inefficient, since it means the length coercion
and CoerceToDomain will actually be executed for each inserted row,
though they could be const-folded away in most cases. Worse, it
seems possible that missing preprocessing for the length coercion
could result in an invalid plan (for example, due to failing to
perform default-function-argument insertion). I'm not aware of
any live bug of that sort with core datatypes, and it might be
unreachable for extension types as well because of restrictions of
CREATE CAST, but I'm not entirely convinced that it's unreachable.
Hence, it seems worth back-patching the fix (although I only went
back to v14, as the patch doesn't apply cleanly at all in v13).
There are several places in the rewriter that are building null
domain constants the same way as preptlist.c. While those are
before the planner and hence don't have any reachable bug, they're
still applying a length coercion that will be const-folded away
later, uselessly wasting cycles. Hence, make a utility routine
that all of these places can call to do it right.
Making this code more careful about the typmod assigned to the
generated NULL constant has visible but cosmetic effects on some
of the plans shown in contrib/postgres_fdw's regression tests.
Discussion: https://postgr.es/m/1865579.1738113656@sss.pgh.pa.us
Backpatch-through: 14
When running on Windows, canonicalize_path() converts '\' to '/'
to prevent confusing the Windows command processor. It was
doing that in a non-encoding-aware fashion; but in SJIS there
are valid two-byte characters whose second byte matches '\'.
So encoding corruption ensues if such a character is used in
the path.
We can fairly easily fix this if we know which encoding is
in use, but a lot of our utilities don't have much of a clue
about that. After some discussion we decided we'd settle for
fixing this only in psql, and assuming that its value of
client_encoding matches what the user is typing.
It seems hopeless to get the server to deal with the problematic
characters in database path names, so we'll just declare that
case to be unsupported. That means nothing need be done in
the server, nor in utility programs whose only contact with
file path names is for database paths. But psql frequently
deals with client-side file paths, so it'd be good if it
didn't mess those up.
Bug: #18735
Reported-by: Koichi Suzuki <koichi.suzuki@enterprisedb.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Koichi Suzuki <koichi.suzuki@enterprisedb.com>
Discussion: https://postgr.es/m/18735-4acdb3998bb9f2b1@postgresql.org
Backpatch-through: 13
The right mix of DDL and VACUUM could corrupt a catalog page header such
that PageIsVerified() durably fails, requiring a restore from backup.
This affects only catalogs that both have a syscache and have DDL code
that uses syscache tuples to construct updates. One of the test
permutations shows a variant not yet fixed.
This makes !TransactionIdIsValid(TM_FailureData.xmax) possible with
TM_Deleted. I think core and PGXN are indifferent to that.
Per bug #17821 from Alexander Lakhin. Back-patch to v13 (all supported
versions). The test case is v17+, since it uses INJECTION_POINT.
Discussion: https://postgr.es/m/17821-dd8c334263399284@postgresql.org
Since commit 757fb0e5a9, these
Informix-compat functions return 0 without changing the output
parameter. Initialize the output parameter before the test call, making
that obvious. Before this, the expected test output has been depending
on freed stack memory. "gcc -ftrivial-auto-var-init=pattern" revealed
that. Back-patch to v13 (all supported versions).
Discussion: https://postgr.es/m/20250106192748.cf.nmisch@google.com
This practice avoids possible problems caused by non-default psql
options, such as disabling AUTOCOMMIT.
Author: Shinya Kato <Shinya11.Kato@oss.nttdata.com>
Reviewed-by: Robert Treat <rob@xzilla.net>
Discussion: https://postgr.es/m/96ff23a5d858ff72ca8e823a014d16fe@oss.nttdata.com
Backpatch-through: 13
The sizeof() call should reference buffer.data, because that's the
buffer we're reading data into, not the whole PGAlignedBuffer union.
This was introduced by 44cac93464, which replaced the simple buffer
with a PGAlignedBuffer field.
It's benign, because the buffer is the largest field of the union, so
the sizes are the same. But it's easy to trip over this in a patch, so
fix and backpatch. Commit 44cac93464 went into 12, but that's EOL.
Backpatch-through: 13
Discussion: https://postgr.es/m/928bdab1-6567-449f-98c4-339cd2203b87@vondra.me
We thought that this condition was unreachable in ExitPostmaster,
but actually it's possible if you have both a misconfigured locale
setting and some other mistake that causes PostmasterMain to bail
out before reaching its own check of pthread_is_threaded_np().
Given the lack of other reports, let's not ask for bug reports if
this occurs; instead just give the same hint as in PostmasterMain.
Bug: #18783
Reported-by: anani191181515@gmail.com
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/18783-d1873b95a59b9103@postgresql.org
Discussion: https://postgr.es/m/206317.1737656533@sss.pgh.pa.us
Backpatch-through: 13
This patch fixes two distinct errors that both ultimately trace
to commit 71d60e2aa, which added the ats_modifiedcols field.
The more severe error is that ats_modifiedcols wasn't accounted for
in afterTriggerAddEvent's scanning loop that looks for a pre-existing
duplicate AfterTriggerSharedData. Thus, a new event could be
incorrectly matched to an AfterTriggerSharedData that has a different
value of ats_modifiedcols, resulting in the wrong tg_updatedcols
bitmap getting passed to the trigger whenever it finally gets fired.
We'd not noticed because (a) few triggers consult tg_updatedcols,
and (b) we had no tests exercising a case where such a trigger was
called as an AFTER trigger. In the test case added by this commit,
contrib/lo's trigger fails to remove a large object when expected
because (without this fix) it thinks the LO OID column hasn't changed.
The other problem was introduced by commit ce5aaea8c, which copied the
modified-columns bitmap into trigger-related storage. It made a copy
for every trigger event, whereas what we really want is to make a new
copy only when we make a new AfterTriggerSharedData entry. (We could
imagine adding extra logic to reduce the number of bitmap copies still
more, but it doesn't look worthwhile at the moment.) In a simple test
of an UPDATE of 10000000 rows with a single AFTER trigger, this thinko
roughly tripled the amount of memory consumed by the pending-triggers
data structures, from 160446744 to 480443440 bytes.
Fixing the first problem requires introducing a bms_equal() call into
afterTriggerAddEvent's scanning loop, which is slightly annoying from
a speed perspective. However, getting rid of the excessive bms_copy()
calls from the second problem balances that out; overall speed of
trigger operations is the same or slightly better, in my tests.
Discussion: https://postgr.es/m/3496294.1737501591@sss.pgh.pa.us
Backpatch-through: 13
In common cases, foreign keys are defined on the toplevel partitioned
table; but if instead one is defined on a partition and references a
partitioned table, and the referencing partition is detached, we would
examine the pg_constraint row on the partition being detached, and fail
to realize that the sub-constraints must be left alone. This causes the
ALTER TABLE DETACH process to fail with
ERROR: could not find ON INSERT check triggers of foreign key constraint NNN
This is similar but not quite the same as what was fixed by
53af9491a0. This bug doesn't affect branches earlier than 15, because
the detach procedure was different there, so we only backpatch down to
15.
Fix by skipping such modifying constraints that are children of other
constraints being detached.
Author: Amul Sul <sulamul@gmail.com>
Diagnosys-by: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/CAAJ_b97GuPh6wQPbxQS-Zpy16Oh+0aMv-w64QcGrLhCOZZ6p+g@mail.gmail.com
The freshly-released 2025a version of tzdata has a refined estimate
for the longitude of Manila, changing their value for LMT in
pre-standardized-timezone days. This changes the output of one of
our test cases. Since we need to be able to run with system tzdata
files that may or may not contain this update, we'd better stop
making that specific test.
I switched it to use Asia/Singapore, which has a roughly similar UTC
offset. That LMT value hasn't changed in tzdb since 2003, so we can
hope that it's well established.
I also noticed that this set of make_timestamptz tests only exercises
zones east of Greenwich, which seems rather sad, and was not the
original intent AFAICS. (We've already changed these tests once
to stabilize their results across tzdata updates, cf 66b737cd9;
it looks like I failed to consider the UTC-offset-sign aspect then.)
To improve that, add a test with Pacific/Honolulu. That LMT offset
is also quite old in tzdb, so we'll cross our fingers that it doesn't
get improved.
Reported-by: Christoph Berg <cb@df7cb.de>
Discussion: https://postgr.es/m/Z46inkznCxesvDEb@msg.df7cb.de
Backpatch-through: 13
If a WaitEventSetWait() caller asks for multiple events, an already set
latch would previously prevent other events from being reported at the
same time. Now, we'll also poll the kernel for other events that would
fit in the caller's output buffer with a zero wait time. This policy
change doesn't affect callers that ask for only one event.
The main caller affected is the postmaster. If its latch is set
extremely frequently by backends launching workers and workers exiting,
we don't want it to handle only those jobs and ignore incoming client
connections.
Back-patch to 16 where the postmaster began using the API. The
fast-return policy changed here is older than that, but doesn't cause
any known problems in earlier releases.
Reported-by: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/Z1n5UpAiGDmFcMmd%40nathan
XLogPageRead() checks immediately for an invalid WAL record header on a
standby, to be able to handle the case of continuation records that need
to be read across two different sources. As written, the check was too
generic, applying to any target LSN. Based on an analysis by Kyotaro
Horiguchi, what really matters is to make sure that the page header is
checked when attempting to read a LSN at the boundary of a segment, to
handle the case of a continuation record that spawns across multiple
pages when dealing with multiple segments, as WAL receivers are spawned
they request WAL from the beginning of a segment. This fix has been
proposed by Kyotaro Horiguchi.
This could cause standbys to loop infinitely when dealing with a
continuation record during a timeline jump, in the case where the
contents of the record in the follow-up page are invalid.
Some regression tests are added to check such scenarios, able to
reproduce the original problem. In the test, the contents of a
continuation record are overwritten with junk zeros on its follow-up
page, and replayed on standbys. This is inspired by 039_end_of_wal.pl,
and is enough to show how standbys should react on promotion by not
being stuck. Without the fix, the test would fail with a timeout. The
test to reproduce the problem has been written by Alexander Kukushkin.
The original check has been introduced in 0668719801, for a similar
problem.
Author: Kyotaro Horiguchi, Alexander Kukushkin
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/CAFh8B=mozC+e1wGJq0H=0O65goZju+6ab5AU7DEWCSUA2OtwDg@mail.gmail.com
Backpatch-through: 13
Tom Lane