The implementation of readdir() in src/port/ which gets used by MSVC has
been added in 399a36a, and since the beginning it considers all errors
on the first file lookup as ENOENT, setting errno accordingly and
letting the routine caller think that the directory is empty. While
this is normally enough for the case of the backend, this can confuse
callers of this routine on Windows as all errors would map to the same
behavior. So, for example, even permission errors would be thought as
having an empty directory, while there could be contents in it.
This commit changes the error handling so as readdir() gets a behavior
similar to native implementations: force errno=0 when seeing
ERROR_FILE_NOT_FOUND as error and consider other errors as plain
failures.
While looking at the patch, I noticed that MinGW does not enforce
errno=0 when looking at the first file, but it gets enforced on the next
file lookups. A comment related to that was incorrect in the code.
Reported-by: Yuri Kurenkov
Diagnosed-by: Yuri Kurenkov, Grigory Smolkin
Author: Konstantin Knizhnik
Reviewed-by: Andrew Dunstan, Michael Paquier
Discussion: https://postgr.es/m/2cad7829-8d66-e39c-b937-ac825db5203d@postgrespro.ru
Backpatch-through: 9.4
Recent OpenBSD (at least 5.9 and up) has a version of getopt(3)
that will not cope with the "-:" spec we use to accept double-dash
options in postgres.c and postmaster.c. Admittedly, that's a hack
because POSIX only requires getopt() to allow alphanumeric option
characters. I have no desire to find another way, however, so
let's just do what we were already doing on Solaris: force use
of our own src/port/getopt.c implementation.
In passing, improve some of the comments around said implementation.
Per buildfarm and local testing. Back-patch to all supported branches.
Discussion: https://postgr.es/m/30197.1547835700@sss.pgh.pa.us
Previously, we used the platform's NL_ARGMAX if any, otherwise 16.
The trouble with this is that the platform value is hugely variable,
ranging from the POSIX-minimum 9 to as much as 64K on recent FreeBSD.
Values of more than a dozen or two have no practical use and slow down
the initialization of the argtypes array. Worse, they cause snprintf.c
to consume far more stack space than was the design intention, possibly
resulting in stack-overflow crashes.
Standardize on 31, which is comfortably more than we need (it looks like
no existing translatable message has more than about 10 parameters).
I chose that, not 32, to make the array sizes powers of 2, for some
possible small gain in speed of the memset.
The lack of reported crashes suggests that the set of platforms we
use snprintf.c on (in released branches) may have no overlap with
the set where NL_ARGMAX has unreasonably large values. But that's
not entirely clear, so back-patch to all supported branches.
Per report from Mateusz Guzik (via Thomas Munro).
Discussion: https://postgr.es/m/CAEepm=3VF=PUp2f8gU8fgZB22yPE_KBS0+e1AHAtQ=09schTHg@mail.gmail.com
Adjust the way we detect the locale. As a result the minumum Windows
version supported by VS2015 and later is Windows Vista. Add some tweaks
to remove new compiler warnings. Remove documentation references to the
now obsolete msysGit.
Michael Paquier, somewhat edited by me, reviewed by Christian Ullrich.
Rather belated backpatch to 9.4 and 9.3
C99 says that the result should be the number of bytes that would have
been emitted given a large enough buffer, not the number we actually
were able to put in the buffer. It's time to make our substitute
implementation comply with that. Not doing so results in inefficiency
in buffer-enlargement cases, and also poses a portability hazard for
third-party code that might expect C99-compliant snprintf behavior
within Postgres.
In passing, remove useless tests for str == NULL; neither C99 nor
predecessor standards ever allowed that except when count == 0,
so I see no reason to expend cycles on making that a non-crash case
for this implementation. Also, don't waste a byte in pg_vfprintf's
local I/O buffer; this might have performance benefits by allowing
aligned writes during flushbuffer calls.
Back-patch of commit 805889d7d. There was some concern about this
possibly breaking code that assumes pre-C99 behavior, but there is
much more risk (and reality, in our own code) of code that assumes
C99 behavior and hence fails to detect buffer overrun without this.
Discussion: https://postgr.es/m/17245.1534289329@sss.pgh.pa.us
Fix a small number of places that were testing the result of snprintf()
but doing so incorrectly. The right test for buffer overrun, per C99,
is "result >= bufsize" not "result > bufsize". Some places were also
checking for failure with "result == -1", but the standard only says
that a negative value is delivered on failure.
(Note that this only makes these places correct if snprintf() delivers
C99-compliant results. But at least now these places are consistent
with all the other places where we assume that.)
Also, make psql_start_test() and isolation_start_test() check for
buffer overrun while constructing their shell commands. There seems
like a higher risk of overrun, with more severe consequences, here
than there is for the individual file paths that are made elsewhere
in the same functions, so this seemed like a worthwhile change.
Also fix guc.c's do_serialize() to initialize errno = 0 before
calling vsnprintf. In principle, this should be unnecessary because
vsnprintf should have set errno if it returns a failure indication ...
but the other two places this coding pattern is cribbed from don't
assume that, so let's be consistent.
These errors are all very old, so back-patch as appropriate. I think
that only the shell command overrun cases are even theoretically
reachable in practice, but there's not much point in erroneous error
checks.
Discussion: https://postgr.es/m/17245.1534289329@sss.pgh.pa.us
If echo = false, simple_prompt() is supposed to prevent echoing the
input (for password input). However, the Windows implementation applied
the mode change to STD_INPUT_HANDLE. That would not have the desired
effect if stdin isn't actually the terminal, for instance if the user
is piping something into psql. Fix it to apply the mode change to
the correct input file, so that passwords do not echo in such cases.
In passing, shorten and de-uglify this code by using #elif rather than
an #if nest and removing some duplicated code.
Back-patch to all supported versions. To simplify that, also back-patch
the portions of commit 9daec77e1 that got rid of an unnecessary
malloc/free in the same area.
Matthew Stickney (cosmetic changes by me)
Discussion: https://postgr.es/m/502a1fff-862b-da52-1031-f68df6ed5a2d@gmail.com
The POSIX standard does not say that the success return value for
fcntl(F_SETFD) and fcntl(F_SETFL) is zero; it says only that it's not -1.
We had several calls that were making the stronger assumption. Adjust
them to test specifically for -1 for strict spec compliance.
The standard further leaves open the possibility that the O_NONBLOCK
flag bit is not the only active one in F_SETFL's argument. Formally,
therefore, one ought to get the current flags with F_GETFL and store
them back with only the O_NONBLOCK bit changed when trying to change
the nonblock state. In port/noblock.c, we were doing the full pushup
in pg_set_block but not in pg_set_noblock, which is just weird. Make
both of them do it properly, since they have little business making
any assumptions about the socket they're handed. The other places
where we're issuing F_SETFL are working with FDs we just got from
pipe(2), so it's reasonable to assume the FDs' properties are all
default, so I didn't bother adding F_GETFL steps there.
Also, while pg_set_block deserves some points for trying to do things
right, somebody had decided that it'd be even better to cast fcntl's
third argument to "long". Which is completely loony, because POSIX
clearly says the third argument for an F_SETFL call is "int".
Given the lack of field complaints, these missteps apparently are not
of significance on any common platforms. But they're still wrong,
so back-patch to all supported branches.
Discussion: https://postgr.es/m/30882.1492800880@sss.pgh.pa.us
This has no effect in the most conventional case, where no relevant DLL
uses a debug build. For an example where it does matter, given a debug
build of MIT Kerberos, the krb_server_keyfile parameter usually had no
effect. Since nobody wants a Heisenbug, back-patch to 9.2 (all
supported versions).
Christian Ullrich, reviewed by Michael Paquier.
In accordance with its own documentation, invoke CloseHandle() only when
directed in the documentation for the function that furnished the
handle. GetModuleHandle() does not so direct. We have been issuing
this call only in the rare event that a CRT DLL contains no "_putenv"
symbol, so lack of bug reports is uninformative. Back-patch to 9.2 (all
supported versions).
Christian Ullrich, reviewed by Michael Paquier.
Replace use of plain 0 as a null pointer constant. In comments, update
terminology and lessen redundancy. Back-patch to 9.2 (all supported
versions) for the convenience of back-patching the next two commits.
Christian Ullrich and Noah Misch, reviewed (in earlier versions) by
Michael Paquier.
<sys/select.h> is required by POSIX.1-2001 to get the prototype of
select(2), but nearly no systems enforce that because older standards
let you get away with including some other headers. Recent OpenBSD
hacking has removed that frail touch of friendliness, however, which
broke some compiles; fix all the way back to 9.1 by adding the required
standard. Only vacuumdb.c was reported to fail, but it seems easier to
fix the whole lot in a fell swoop.
Per bug #14334 by Sean Farrell.
Whenever this function is used with the FORMAT_MESSAGE_FROM_SYSTEM flag,
it's good practice to include FORMAT_MESSAGE_IGNORE_INSERTS as well.
Otherwise, if the message contains any %n insertion markers, the function
will try to fetch argument strings to substitute --- which we are not
passing, possibly leading to a crash. This is exactly analogous to the
rule about not giving printf() a format string you're not in control of.
Noted and patched by Christian Ullrich.
Back-patch to all supported branches.
The POSIX standard for tar headers requires archive member sizes to be
printed in octal with at most 11 digits, limiting the representable file
size to 8GB. However, GNU tar and apparently most other modern tars
support a convention in which oversized values can be stored in base-256,
allowing any practical file to be a tar member. Adopt this convention
to remove two limitations:
* pg_dump with -Ft output format failed if the contents of any one table
exceeded 8GB.
* pg_basebackup failed if the data directory contained any file exceeding
8GB. (This would be a fatal problem for installations configured with a
table segment size of 8GB or more, and it has also been seen to fail when
large core dump files exist in the data directory.)
File sizes under 8GB are still printed in octal, so that no compatibility
issues are created except in cases that would have failed entirely before.
In addition, this patch fixes several bugs in the same area:
* In 9.3 and later, we'd defined tarCreateHeader's file-size argument as
size_t, which meant that on 32-bit machines it would write a corrupt tar
header for file sizes between 4GB and 8GB, even though no error was raised.
This broke both "pg_dump -Ft" and pg_basebackup for such cases.
* pg_restore from a tar archive would fail on tables of size between 4GB
and 8GB, on machines where either "size_t" or "unsigned long" is 32 bits.
This happened even with an archive file not affected by the previous bug.
* pg_basebackup would fail if there were files of size between 4GB and 8GB,
even on 64-bit machines.
* In 9.3 and later, "pg_basebackup -Ft" failed entirely, for any file size,
on 64-bit big-endian machines.
In view of these potential data-loss bugs, back-patch to all supported
branches, even though removal of the documented 8GB limit might otherwise
be considered a new feature rather than a bug fix.
It's standard for quicksort implementations, after having partitioned the
input into two subgroups, to recurse to process the smaller partition and
then handle the larger partition by iterating. This method guarantees
that no more than log2(N) levels of recursion can be needed. However,
Bentley and McIlroy argued that checking to see which partition is smaller
isn't worth the cycles, and so their code doesn't do that but just always
recurses on the left partition. In most cases that's fine; but with
worst-case input we might need O(N) levels of recursion, and that means
that qsort could be driven to stack overflow. Such an overflow seems to
be the only explanation for today's report from Yiqing Jin of a SIGSEGV
in med3_tuple while creating an index of a couple billion entries with a
very large maintenance_work_mem setting. Therefore, let's spend the few
additional cycles and lines of code needed to choose the smaller partition
for recursion.
Also, fix up the qsort code so that it properly uses size_t not int for
some intermediate values representing numbers of items. This would only
be a live risk when sorting more than INT_MAX bytes (in qsort/qsort_arg)
or tuples (in qsort_tuple), which I believe would never happen with any
caller in the current core code --- but perhaps it could happen with
call sites in third-party modules? In any case, this is trouble waiting
to happen, and the corrected code is probably if anything shorter and
faster than before, since it removes sign-extension steps that had to
happen when converting between int and size_t.
In passing, move a couple of CHECK_FOR_INTERRUPTS() calls so that it's
not necessary to preserve the value of "r" across them, and prettify
the output of gen_qsort_tuple.pl a little.
Back-patch to all supported branches. The odds of hitting this issue
are probably higher in 9.4 and up than before, due to the new ability
to allocate sort workspaces exceeding 1GB, but there's no good reason
to believe that it's impossible to crash older branches this way.
This supplements the GNU libc bug #6530 workarounds introduced in commit
54cd4f0457. On affected systems, a
tar-format pg_basebackup failed when some filename beneath the data
directory was not valid character data in the postmaster/walsender
locale. Back-patch to 9.1, where pg_basebackup was introduced. Extant,
bug-prone conversion specifications receive only ASCII bytes or involve
low-importance messages.
This reverts commit 16304a0134, except
for its changes in src/port/snprintf.c; as well as commit
cac18a76bb which is no longer needed.
Fujii Masao reported that the previous commit caused failures in psql on
OS X, since if one exits the pager program early while viewing a query
result, psql sees an EPIPE error from fprintf --- and the wrapper function
thought that was reason to panic. (It's a bit surprising that the same
does not happen on Linux.) Further discussion among the security list
concluded that the risk of other such failures was far too great, and
that the one-size-fits-all approach to error handling embodied in the
previous patch is unlikely to be workable.
This leaves us again exposed to the possibility of the type of failure
envisioned in CVE-2015-3166. However, that failure mode is strictly
hypothetical at this point: there is no concrete reason to believe that
an attacker could trigger information disclosure through the supposed
mechanism. In the first place, the attack surface is fairly limited,
since so much of what the backend does with format strings goes through
stringinfo.c or psprintf(), and those already had adequate defenses.
In the second place, even granting that an unprivileged attacker could
control the occurrence of ENOMEM with some precision, it's a stretch to
believe that he could induce it just where the target buffer contains some
valuable information. So we concluded that the risk of non-hypothetical
problems induced by the patch greatly outweighs the security risks.
We will therefore revert, and instead undertake closer analysis to
identify specific calls that may need hardening, rather than attempt a
universal solution.
We have kept the portion of the previous patch that improved snprintf.c's
handling of errors when it calls the platform's sprintf(). That seems to
be an unalloyed improvement.
Security: CVE-2015-3166
All known standard library implementations of these functions can fail
with ENOMEM. A caller neglecting to check for failure would experience
missing output, information exposure, or a crash. Check return values
within wrappers and code, currently just snprintf.c, that bypasses the
wrappers. The wrappers do not return after an error, so their callers
need not check. Back-patch to 9.0 (all supported versions).
Popular free software standard library implementations do take pains to
bypass malloc() in simple cases, but they risk ENOMEM for floating point
numbers, positional arguments, large field widths, and large precisions.
No specification demands such caution, so this commit regards every call
to a printf family function as a potential threat.
Injecting the wrappers implicitly is a compromise between patch scope
and design goals. I would prefer to edit each call site to name a
wrapper explicitly. libpq and the ECPG libraries would, ideally, convey
errors to the caller rather than abort(). All that would be painfully
invasive for a back-patched security fix, hence this compromise.
Security: CVE-2015-3166
Since commit ba7c5975ad, port/dirmod.c
has contained only Windows-specific functions. Most platforms don't
seem to mind uselessly building an empty file, but OS X for one issues
warnings. Hence, treat dirmod.c as a Windows-specific file selected
by configure rather than one that's always built. We can revert this
change if dirmod.c ever gains any non-Windows functionality again.
Back-patch to 9.4 where the mentioned commit appeared.
When the library already exists in the build directory, "ar" preserves
members not named on its command line. This mattered when, for example,
a "configure" rerun dropped a file from $(LIBOBJS). libpgport carried
the obsolete member until "make clean". Back-patch to 9.0 (all
supported versions).
Avoid losing errno if readdir() fails and closedir() works. Consistently
return 4 rather than 3 if both a lost+found directory and other files are
found, rather than returning one value or the other depending on the
order of the directory listing. Update comments to match the actual
behavior.
These oversights date to commits 6f03927fce
and 17f1523932.
Marco Nenciarini
On windows _isnan() (which isnan() is redirected to in port/win32.h)
is declared in float.h, not math.h.
Per buildfarm animal currawong.
Backpatch to all supported branches.
Prevent port/snprintf() from overflowing its local fixed-size
buffer and pad to the desired number of digits with zeros, even
if the precision is beyond the ability of the native sprintf().
port/snprintf() is only used on systems that lack a native
snprintf().
Reported by Bruce Momjian. Patch by Tom Lane. Backpatch to all
supported versions.
Security: CVE-2015-0242
Previous fix mapped "Norwegian (Bokmål)" locale, which contains a non-ASCII
character, to the pure ASCII alias "norwegian-bokmal". However, it turns
out that more recent versions of the CRT library, in particular MSVCR110
(Visual Studio 2012), changed the behaviour of setlocale() so that if
you pass "norwegian-bokmal" to setlocale, it returns "Norwegian_Norway".
That meant trouble, when setlocale(..., NULL) first returned
"Norwegian (Bokmål)_Norway", which we mapped to "norwegian-bokmal_Norway",
but another call to setlocale(..., "norwegian-bokmal_Norway") returned
"Norwegian_Norway". That caused PostgreSQL to think that they are different
locales, and therefore not compatible. That caused initdb to fail at
CREATE DATABASE.
Older CRT versions seem to accept "Norwegian_Norway" too, so change the
mapping to return "Norwegian_Norway" instead of "norwegian-bokmal".
Backpatch to 9.2 like the previous attempt. We haven't made a release that
includes the previous fix yet, so we don't need to worry about changing the
locale of existing clusters from "norwegian-bokmal" to "Norwegian_Norway".
(Doing any mapping like this at all requires changing the locale of
existing databases; the release notes need to include instructions for
that).
Some users run their applications in chroot environments that lack an
/etc/passwd file. This means that the current UID's user name and home
directory are not obtainable. libpq used to be all right with that,
so long as the database role name to use was specified explicitly.
But commit a4c8f14364 broke such cases by
causing any failure of pg_fe_getauthname() to be treated as a hard error.
In any case it did little to advance its nominal goal of causing errors
in pg_fe_getauthname() to be reported better. So revert that and instead
put some real error-reporting code in place. This requires changes to the
APIs of pg_fe_getauthname() and pqGetpwuid(), since the latter had
departed from the POSIX-specified API of getpwuid_r() in a way that made
it impossible to distinguish actual lookup errors from "no such user".
To allow such failures to be reported, while not failing if the caller
supplies a role name, add a second call of pg_fe_getauthname() in
connectOptions2(). This is a tad ugly, and could perhaps be avoided with
some refactoring of PQsetdbLogin(), but I'll leave that idea for later.
(Note that the complained-of misbehavior only occurs in PQsetdbLogin,
not when using the PQconnect functions, because in the latter we will
never bother to call pg_fe_getauthname() if the user gives a role name.)
In passing also clean up the Windows-side usage of GetUserName(): the
recommended buffer size is 257 bytes, the passed buffer length should
be the buffer size not buffer size less 1, and any error is reported
by GetLastError() not errno.
Per report from Christoph Berg. Back-patch to 9.4 where the chroot
failure case was introduced. The generally poor reporting of errors
here is of very long standing, of course, but given the lack of field
complaints about it we won't risk changing these APIs further back
(even though they're theoretically internal to libpq).
