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postgresql: Security Advisory-postgresql-CVE-2016-0773
add CVE-2016-0773 patch for avoiding attackers to cause a denial of service (infinite loop or buffer overflow and crash) via a large Unicode character range in a regular expression. Patch comes from: http://git.postgresql.org/gitweb/?p=postgresql.git;a=summary commit 3bb3f42f3749d40b8d4de65871e8d828b18d4a45 Signed-off-by: Zhixiong Chi <Zhixiong.Chi@windriver.com> Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
This commit is contained in:
Zhixiong Chi
committed by
Martin Jansa
Martin Jansa
parent
35d91f32c4
commit
8354a07d12
@@ -0,0 +1,222 @@
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From 3bb3f42f3749d40b8d4de65871e8d828b18d4a45 Mon Sep 17 00:00:00 2001
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From: Tom Lane <tgl@sss.pgh.pa.us>
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Date: Mon, 8 Feb 2016 10:25:40 -0500
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Subject: [PATCH] Fix some regex issues with out-of-range characters and large
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char ranges.
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Previously, our regex code defined CHR_MAX as 0xfffffffe, which is a
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bad choice because it is outside the range of type "celt" (int32).
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Characters approaching that limit could lead to infinite loops in logic
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such as "for (c = a; c <= b; c++)" where c is of type celt but the
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range bounds are chr. Such loops will work safely only if CHR_MAX+1
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is representable in celt, since c must advance to beyond b before the
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loop will exit.
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Fortunately, there seems no reason not to restrict CHR_MAX to 0x7ffffffe.
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It's highly unlikely that Unicode will ever assign codes that high, and
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none of our other backend encodings need characters beyond that either.
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In addition to modifying the macro, we have to explicitly enforce character
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range restrictions on the values of \u, \U, and \x escape sequences, else
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the limit is trivially bypassed.
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Also, the code for expanding case-independent character ranges in bracket
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expressions had a potential integer overflow in its calculation of the
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number of characters it could generate, which could lead to allocating too
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small a character vector and then overwriting memory. An attacker with the
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ability to supply arbitrary regex patterns could easily cause transient DOS
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via server crashes, and the possibility for privilege escalation has not
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been ruled out.
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Quite aside from the integer-overflow problem, the range expansion code was
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unnecessarily inefficient in that it always produced a result consisting of
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individual characters, abandoning the knowledge that we had a range to
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start with. If the input range is large, this requires excessive memory.
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Change it so that the original range is reported as-is, and then we add on
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any case-equivalent characters that are outside that range. With this
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approach, we can bound the number of individual characters allowed without
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sacrificing much. This patch allows at most 100000 individual characters,
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which I believe to be more than the number of case pairs existing in
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Unicode, so that the restriction will never be hit in practice.
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It's still possible for range() to take awhile given a large character code
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range, so also add statement-cancel detection to its loop. The downstream
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function dovec() also lacked cancel detection, and could take a long time
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given a large output from range().
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Per fuzz testing by Greg Stark. Back-patch to all supported branches.
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Security: CVE-2016-0773
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Upstream-Status: Backport
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Signed-off-by: Tom Lane <tgl@sss.pgh.pa.us>
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Signed-off-by: Zhixiong Chi <zhixiong.chi@windriver.com>
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Index: postgresql-9.4.5/src/backend/regex/regc_lex.c
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===================================================================
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--- postgresql-9.4.5.orig/src/backend/regex/regc_lex.c 2015-10-06 03:12:06.000000000 +0800
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+++ postgresql-9.4.5/src/backend/regex/regc_lex.c 2016-03-10 10:29:57.045784317 +0800
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@@ -792,13 +792,13 @@
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break;
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case CHR('u'):
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c = lexdigits(v, 16, 4, 4);
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- if (ISERR())
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+ if (ISERR() || c < CHR_MIN || c > CHR_MAX)
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FAILW(REG_EESCAPE);
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RETV(PLAIN, c);
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break;
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case CHR('U'):
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c = lexdigits(v, 16, 8, 8);
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- if (ISERR())
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+ if (ISERR() || c < CHR_MIN || c > CHR_MAX)
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FAILW(REG_EESCAPE);
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RETV(PLAIN, c);
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break;
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@@ -816,7 +816,7 @@
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case CHR('x'):
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NOTE(REG_UUNPORT);
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c = lexdigits(v, 16, 1, 255); /* REs >255 long outside spec */
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- if (ISERR())
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+ if (ISERR() || c < CHR_MIN || c > CHR_MAX)
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FAILW(REG_EESCAPE);
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RETV(PLAIN, c);
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break;
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@@ -872,6 +872,9 @@
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/*
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* lexdigits - slurp up digits and return chr value
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+ *
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+ * This does not account for overflow; callers should range-check the result
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+ * if maxlen is large enough to make that possible.
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*/
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static chr /* chr value; errors signalled via ERR */
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lexdigits(struct vars * v,
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Index: postgresql-9.4.5/src/backend/regex/regc_locale.c
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===================================================================
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--- postgresql-9.4.5.orig/src/backend/regex/regc_locale.c 2015-10-06 03:12:06.000000000 +0800
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+++ postgresql-9.4.5/src/backend/regex/regc_locale.c 2016-03-10 10:34:28.757781726 +0800
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@@ -408,8 +408,7 @@
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int nchrs;
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struct cvec *cv;
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celt c,
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- lc,
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- uc;
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+ cc;
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if (a != b && !before(a, b))
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{
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@@ -427,24 +426,48 @@
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/*
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* When case-independent, it's hard to decide when cvec ranges are usable,
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- * so for now at least, we won't try. We allocate enough space for two
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- * case variants plus a little extra for the two title case variants.
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+ * so for now at least, we won't try. We use a range for the originally
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+ * specified chrs and then add on any case-equivalents that are outside
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+ * that range as individual chrs.
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+ *
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+ * To ensure sane behavior if someone specifies a very large range, limit
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+ * the allocation size to 100000 chrs (arbitrary) and check for overrun
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+ * inside the loop below.
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*/
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- nchrs = (b - a + 1) * 2 + 4;
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-
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- cv = getcvec(v, nchrs, 0);
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+ cv = getcvec(v, nchrs, 1);
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NOERRN();
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+ addrange(cv, a, b);
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for (c = a; c <= b; c++)
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{
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- addchr(cv, c);
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- lc = pg_wc_tolower((chr) c);
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- if (c != lc)
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- addchr(cv, lc);
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- uc = pg_wc_toupper((chr) c);
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- if (c != uc)
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- addchr(cv, uc);
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+ cc = pg_wc_tolower((chr) c);
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+ if (cc != c &&
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+ (before(cc, a) || before(b, cc)))
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+ {
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+ if (cv->nchrs >= cv->chrspace)
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+ {
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+ ERR(REG_ETOOBIG);
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+ return NULL;
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+ }
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+ addchr(cv, cc);
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+ }
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+ cc = pg_wc_toupper((chr) c);
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+ if (cc != c &&
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+ (before(cc, a) || before(b, cc)))
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+ {
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+ if (cv->nchrs >= cv->chrspace)
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+ {
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+ ERR(REG_ETOOBIG);
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+ return NULL;
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+ }
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+ addchr(cv, cc);
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+ }
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+ if (CANCEL_REQUESTED(v->re))
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+ {
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+ ERR(REG_CANCEL);
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+ return NULL;
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+ }
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}
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return cv;
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Index: postgresql-9.4.5/src/backend/regex/regcomp.c
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===================================================================
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--- postgresql-9.4.5.orig/src/backend/regex/regcomp.c 2015-10-06 03:12:06.000000000 +0800
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+++ postgresql-9.4.5/src/backend/regex/regcomp.c 2016-03-10 10:35:25.397781185 +0800
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@@ -1569,6 +1569,7 @@
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{
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ch = *p;
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newarc(v->nfa, PLAIN, subcolor(v->cm, ch), lp, rp);
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+ NOERR();
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}
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/* and the ranges */
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@@ -1578,6 +1579,7 @@
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to = *(p + 1);
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if (from <= to)
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subrange(v, from, to, lp, rp);
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+ NOERR();
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}
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}
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Index: postgresql-9.4.5/src/include/regex/regcustom.h
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===================================================================
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--- postgresql-9.4.5.orig/src/include/regex/regcustom.h 2015-10-06 03:12:06.000000000 +0800
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+++ postgresql-9.4.5/src/include/regex/regcustom.h 2016-03-10 10:37:09.989780188 +0800
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@@ -65,7 +65,8 @@
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#define DIGITVAL(c) ((c)-'0') /* turn chr digit into its value */
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#define CHRBITS 32 /* bits in a chr; must not use sizeof */
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#define CHR_MIN 0x00000000 /* smallest and largest chr; the value */
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-#define CHR_MAX 0xfffffffe /* CHR_MAX-CHR_MIN+1 should fit in uchr */
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+#define CHR_MAX 0x7ffffffe /* CHR_MAX-CHR_MIN+1 must fit in an int, and
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+ * CHR_MAX+1 must fit in both chr and celt */
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/* functions operating on chr */
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#define iscalnum(x) pg_wc_isalnum(x)
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Index: postgresql-9.4.5/src/test/regress/expected/regex.out
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===================================================================
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--- postgresql-9.4.5.orig/src/test/regress/expected/regex.out 2015-10-06 03:12:06.000000000 +0800
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+++ postgresql-9.4.5/src/test/regress/expected/regex.out 2016-03-10 10:38:28.821779436 +0800
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@@ -222,3 +222,5 @@
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t
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(1 row)
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+select 'a' ~ '\x7fffffff'; -- invalid chr code
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+ERROR: invalid regular expression: invalid escape \ sequence
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Index: postgresql-9.4.5/src/test/regress/sql/regex.sql
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===================================================================
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--- postgresql-9.4.5.orig/src/test/regress/sql/regex.sql 2015-10-06 03:12:06.000000000 +0800
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+++ postgresql-9.4.5/src/test/regress/sql/regex.sql 2016-03-10 10:38:57.845779159 +0800
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@@ -57,3 +57,4 @@
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select 'a' ~ '.. ()|\1';
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select 'a' ~ '()*\1';
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select 'a' ~ '()+\1';
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+select 'a' ~ '\x7fffffff'; -- invalid chr code
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@@ -32,6 +32,7 @@ SRC_URI = "http://ftp.postgresql.org/pub/source/v${PV}/${BP}.tar.bz2 \
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file://postgresql.service \
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file://0001-Use-pkg-config-for-libxml2-detection.patch \
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file://postgresql-CVE-2016-0766.patch \
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file://postgresql-CVE-2016-0773.patch \
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"
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LEAD_SONAME = "libpq.so"
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