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Previously, our regex code defined CHR_MAX as 0xfffffffe, which is a bad choice because it is outside the range of type "celt" (int32). Characters approaching that limit could lead to infinite loops in logic such as "for (c = a; c <= b; c++)" where c is of type celt but the range bounds are chr. Such loops will work safely only if CHR_MAX+1 is representable in celt, since c must advance to beyond b before the loop will exit. Fortunately, there seems no reason not to restrict CHR_MAX to 0x7ffffffe. It's highly unlikely that Unicode will ever assign codes that high, and none of our other backend encodings need characters beyond that either. In addition to modifying the macro, we have to explicitly enforce character range restrictions on the values of \u, \U, and \x escape sequences, else the limit is trivially bypassed. Also, the code for expanding case-independent character ranges in bracket expressions had a potential integer overflow in its calculation of the number of characters it could generate, which could lead to allocating too small a character vector and then overwriting memory. An attacker with the ability to supply arbitrary regex patterns could easily cause transient DOS via server crashes, and the possibility for privilege escalation has not been ruled out. Quite aside from the integer-overflow problem, the range expansion code was unnecessarily inefficient in that it always produced a result consisting of individual characters, abandoning the knowledge that we had a range to start with. If the input range is large, this requires excessive memory. Change it so that the original range is reported as-is, and then we add on any case-equivalent characters that are outside that range. With this approach, we can bound the number of individual characters allowed without sacrificing much. This patch allows at most 100000 individual characters, which I believe to be more than the number of case pairs existing in Unicode, so that the restriction will never be hit in practice. It's still possible for range() to take awhile given a large character code range, so also add statement-cancel detection to its loop. The downstream function dovec() also lacked cancel detection, and could take a long time given a large output from range(). Per fuzz testing by Greg Stark. Back-patch to all supported branches. Security: CVE-2016-0773 |
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PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: http://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.