| Commit message (Collapse) | Author | Age |
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If pg_regcomp failed after having invoked markst/cleanst, it would leak any
"struct subre" nodes it had created. (We've already detected all regex
syntax errors at that point, so the only likely causes of later failure
would be query cancel or out-of-memory.) To fix, make sure freesrnode
knows the difference between the pre-cleanst and post-cleanst cleanup
procedures. Add some documentation of this less-than-obvious point.
Also, newlacon did the wrong thing with an out-of-memory failure from
realloc(), so that the previously allocated array would be leaked.
Both of these are pretty low-probability scenarios, but a bug is a bug,
so patch all the way back.
Per bug #10976 from Arthur O'Dwyer.
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This was not changed in HEAD, but will be done later as part of a
pgindent run. Future pgindent runs will also do this.
Report by Tom Lane
Backpatch through all supported branches, but not HEAD
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The regex code didn't have any provision for query cancel; which is
unsurprising given its non-Postgres origin, but still problematic since
some operations can take a long time. Introduce a callback function to
check for a pending query cancel or session termination request, and
call it in a couple of strategic spots where we can make the regex code
exit with an error indicator.
If we ever actually split out the regex code as a standalone library,
some additional work will be needed to let the cancel callback function
be specified externally to the library. But that's straightforward
(certainly so by comparison to putting the locale-dependent character
classification logic on a similar arms-length basis), and there seems
no need to do it right now.
A bigger issue is that there may be more places than these two where
we need to check for cancels. We can always add more checks later,
now that the infrastructure is in place.
Since there are known examples of not-terribly-long regexes that can
lock up a backend for a long time, back-patch to all supported branches.
I have hopes of fixing the known performance problems later, but adding
query cancel ability seems like a good idea even if they were all fixed.
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An ancient logic error in cfindloop() could cause the regex engine to fail
to find matches that begin later than the start of the string. This
function is only used when the regex pattern contains a back reference,
and so far as we can tell the error is only reachable if the pattern is
non-greedy (i.e. its first quantifier uses the ? modifier). Furthermore,
the actual match must begin after some potential match that satisfies the
DFA but then fails the back-reference's match test.
Reported and fixed by Jeevan Chalke, with cosmetic adjustments by me.
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Throw an error instead.
Backpatch to all supported branches.
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The previous coding of this function could get into situations where it
would never terminate, because successive passes would re-add EMPTY arcs
that had been removed by the previous pass. Rewrite the function
completely using a new algorithm that is guaranteed to terminate, and
also seems to be usually faster than the old one. Per Tcl bugs 3604074
and 3606683.
Tom Lane and Don Porter
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parseqatom() failed to check for an error return (NULL result) from its
recursive call to parsebranch(), and in consequence could crash with a
null-pointer dereference after an error return. This bug has been there
since day one, but wasn't noticed before, probably because most error cases
in parsebranch() didn't actually lead to returning NULL. Add the missing
error check, and also tweak parsebranch() to exit in a less indirect
fashion after a call to parseqatom() fails.
Report by Tomasz Karlik, fix by me.
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rfree() failed to cope with the case that pg_regcomp() had initialized the
regex_t struct but then failed to allocate any memory for re->re_guts (ie,
the first malloc call in pg_regcomp() failed). It would try to touch the
guts struct anyway, and thus dump core. This is a sufficiently narrow
corner case that it's not surprising it's never been seen in the field;
but still a bug is a bug, so patch all active branches.
Noted while investigating whether we need to call pg_regfree after a
failure return from pg_regcomp. Other than this bug, it turns out we
don't, so adjust comments appropriately.
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Back-patch of commits 628cbb50ba80c83917b07a7609ddec12cda172d0 and
c6aae3042be5249e672b731ebeb21875b5343010. This has been broken since
7.3, so back-patch to all supported branches.
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The syntax "\n*", that is a backref with a * quantifier directly applied
to it, has never worked correctly in Spencer's library. This has been an
open bug in the Tcl bug tracker since 2005:
https://sourceforge.net/tracker/index.php?func=detail&aid=1115587&group_id=10894&atid=110894
The core of the problem is in parseqatom(), which first changes "\n*" to
"\n+|" and then applies repeat() to the NFA representing the backref atom.
repeat() thinks that any arc leading into its "rp" argument is part of the
sub-NFA to be repeated. Unfortunately, since parseqatom() already created
the arc that was intended to represent the empty bypass around "\n+", this
arc gets moved too, so that it now leads into the state loop created by
repeat(). Thus, what was supposed to be an "empty" bypass gets turned into
something that represents zero or more repetitions of the NFA representing
the backref atom. In the original example, in place of
^([bc])\1*$
we now have something that acts like
^([bc])(\1+|[bc]*)$
At runtime, the branch involving the actual backref fails, as it's supposed
to, but then the other branch succeeds anyway.
We could no doubt fix this by some rearrangement of the operations in
parseqatom(), but that code is plenty ugly already, and what's more the
whole business of converting "x*" to "x+|" probably needs to go away to fix
another problem I'll mention in a moment. Instead, this patch suppresses
the *-conversion when the target is a simple backref atom, leaving the case
of m == 0 to be handled at runtime. This makes the patch in regcomp.c a
one-liner, at the cost of having to tweak cbrdissect() a little. In the
event I went a bit further than that and rewrote cbrdissect() to check all
the string-length-related conditions before it starts comparing characters.
It seems a bit stupid to possibly iterate through many copies of an
n-character backreference, only to fail at the end because the target
string's length isn't a multiple of n --- we could have found that out
before starting. The existing coding could only be a win if integer
division is hugely expensive compared to character comparison, but I don't
know of any modern machine where that might be true.
This does not fix all the problems with quantified back-references. In
particular, the code is still broken for back-references that appear within
a larger expression that is quantified (so that direct insertion of the
quantification limits into the BACKREF node doesn't apply). I think fixing
that will take some major surgery on the NFA code, specifically introducing
an explicit iteration node type instead of trying to transform iteration
into concatenation of modified regexps.
Back-patch to all supported branches. In HEAD, also add a regression test
case for this. (It may seem a bit silly to create a regression test file
for just one test case; but I'm expecting that we will soon import a whole
bunch of regex regression tests from Tcl, so might as well create the
infrastructure now.)
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Apparently some compilers dislike a case label with nothing after it.
Per buildfarm.
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This involves getting the character classification and case-folding
functions in the regex library to use the collations infrastructure.
Most of this work had been done already in connection with the upper/lower
and LIKE logic, so it was a simple matter of transposition.
While at it, split out these functions into a separate source file
regc_pg_locale.c, so that they can be correctly labeled with the Postgres
project's license rather than the Scriptics license. These functions are
100% Postgres-written code whereas what remains in regc_locale.c is still
mostly not ours, so lumping them both under the same copyright notice was
getting more and more misleading.
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Per C standard, these are semantically the same thing; but saying NULL
when you mean NULL is good for readability.
Marti Raudsepp, per results of INRIA's Coccinelle.
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from "clang". The VERR changes make an assignment unconditional, which is
probably easier to read/understand anyway, and one can hardly argue that
it's worth shaving cycles off the case of reporting another error when
one has already been detected. The INSIST change limits where that macro
can be used, but not in a way that creates a problem for any existing call.
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matching before recursing instead of after. The DFA match eliminates
unworkable midpoint choices a lot faster than the recursive check, in most
cases, so doing it first can speed things up; particularly in pathological
cases such as recently exhibited by Michael Glaesemann.
In addition, apply some cosmetic changes that were applied upstream (in the
Tcl project) at the same time, in order to sync with upstream version 1.15
of regexec.c.
Upstream apparently intends to backpatch this, so I will too. The
pathological behavior could be unpleasant if encountered in the field,
which seems to justify any risk of introducing new bugs.
Tom Lane, reviewed by Donal K. Fellows of Tcl project
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locale-dependent character classification properly when the database encoding
is UTF8.
The previous coding worked okay in single-byte encodings, or in any case for
ASCII characters, but failed entirely on multibyte characters. The fix
assumes that the <wctype.h> functions use Unicode code points as the wchar
representation for Unicode, ie, wchar matches pg_wchar.
This is only a partial solution, since we're still stupid about non-ASCII
characters in multibyte encodings other than UTF8. The practical effect
of that is limited, however, since those cases are generally Far Eastern
glyphs for which concepts like case-folding don't apply anyway. Certainly
all or nearly all of the field reports of problems have been about UTF8.
A more general solution would require switching to the platform's wchar
representation for all regex operations; which is possible but would have
substantial disadvantages. Let's try this and see if it's sufficient in
practice.
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provided by Andrew.
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was Tcl 8.4.8. The main changes are to remove the never-fully-implemented
code for multi-character collating elements, and to const-ify some stuff a
bit more fully. In combination with the recent security patch, this commit
brings us into line with Tcl 8.5.0.
Note that I didn't make any effort to duplicate a lot of cosmetic changes
that they made to bring their copy into line with their own style
guidelines, such as adding braces around single-line IF bodies. Most of
those we either had done already (such as ANSI-fication of function headers)
or there is no point because pgindent would undo the change anyway.
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are shared with Tcl, since it's their code to begin with, and the patches
have been copied from Tcl 8.5.0. Problems:
CVE-2007-4769: Inadequate check on the range of backref numbers allows
crash due to out-of-bounds read.
CVE-2007-4772: Infinite loop in regex optimizer for pattern '($|^)*'.
CVE-2007-6067: Very slow optimizer cleanup for regex with a large NFA
representation, as well as crash if we encounter an out-of-memory condition
during NFA construction.
Part of the response to CVE-2007-6067 is to put a limit on the number of
states in the NFA representation of a regex. This seems needed even though
the within-the-code problems have been corrected, since otherwise the code
could try to use very large amounts of memory for a suitably-crafted regex,
leading to potential DOS by driving the system into swap, activating a kernel
OOM killer, etc.
Although there are certainly plenty of ways to drive the system into effective
DOS with poorly-written SQL queries, these problems seem worth treating as
security issues because many applications might accept regex search patterns
from untrustworthy sources.
Thanks to Will Drewry of Google for reporting these problems. Patches by Will
Drewry and Tom Lane.
Security: CVE-2007-4769, CVE-2007-4772, CVE-2007-6067
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versions of gcc (I'm seeing it with Apple's gcc 4.0.1). I think the
reason we did not see this before was that the assert() macros in the
regex code were all no-ops till recently.
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as we do (and upstream Tcl doesn't). The loop limit might be subject
to negotiation if anyone ever tries to do regex debugging in Far
Eastern languages, but for now 1000 seems plenty. CHR_MAX was right out :-(
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warnings on a 64-bit machine. Noted while chasing a recent regex
bug report.
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Standard English uses "may", "can", and "might" in different ways:
may - permission, "You may borrow my rake."
can - ability, "I can lift that log."
might - possibility, "It might rain today."
Unfortunately, in conversational English, their use is often mixed, as
in, "You may use this variable to do X", when in fact, "can" is a better
choice. Similarly, "It may crash" is better stated, "It might crash".
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comment line where output as too long, and update typedefs for /lib
directory. Also fix case where identifiers were used as variable names
in the backend, but as typedefs in ecpg (favor the backend for
indenting).
Backpatch to 8.1.X.
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The specification of this function is as follows.
regexp_replace(source text, pattern text, replacement text, [flags
text])
returns text
Replace string that matches to regular expression in source text to
replacement text.
- pattern is regular expression pattern.
- replacement is replace string that can use '\1'-'\9', and '\&'.
'\1'-'\9': back reference to the n'th subexpression.
'\&' : entire matched string.
- flags can use the following values:
g: global (replace all)
i: ignore case
When the flags is not specified, case sensitive, replace the first
instance only.
Atsushi Ogawa
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them, the executation behavior could be unexpected.
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8.4.1). This corrects some curious regex bugs, though not the greediness
issue I was hoping to find a solution for :-(
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conversion of basic ASCII letters. Remove all uses of strcasecmp and
strncasecmp in favor of new functions pg_strcasecmp and pg_strncasecmp;
remove most but not all direct uses of toupper and tolower in favor of
pg_toupper and pg_tolower. These functions use the same notions of
case folding already developed for identifier case conversion. I left
the straight locale-based folding in place for situations where we are
just manipulating user data and not trying to match it to built-in
strings --- for example, the SQL upper() function is still locale
dependent. Perhaps this will prove not to be what's wanted, but at
the moment we can initdb and pass regression tests in Turkish locale.
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Also, make :alnum: character class directly dependent on isalnum()
rather than guessing.
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(extracted from Tcl 8.4.1 release, as Henry still hasn't got round to
making it a separate library). This solves a performance problem for
multibyte, as well as upgrading our regexp support to match recent Tcl
and nearly match recent Perl.
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postgres.h or c.h includes a system header (such as stdio.h or
stdlib.h), there's no need to specifically include it in any of the .c
files in the backend.
Neil Conway
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referring to "multibyte" where it really means character encoding.
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because c.h has sys/types.h.
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Implement SQL99 SIMILAR TO as a synonym for our existing operator "~".
Implement SQL99 regular expression SUBSTRING(string FROM pat FOR escape).
Extend the definition to make the FOR clause optional.
Define textregexsubstr() to actually implement this feature.
Update the regression test to include these new string features.
All tests pass.
Rename the regular expression support routines from "pg95_xxx" to "pg_xxx".
Define CREATE CHARACTER SET in the parser per SQL99. No implementation yet.
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