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antirez 48e24d54b7 Ziplist: insertion bug under particular conditions fixed.
Ziplists had a bug that was discovered while investigating a different
issue, resulting in a corrupted ziplist representation, and a likely
segmentation foult and/or data corruption of the last element of the
ziplist, once the ziplist is accessed again.

The bug happens when a specific set of insertions / deletions is
performed so that an entry is encoded to have a "prevlen" field (the
length of the previous entry) of 5 bytes but with a count that could be
encoded in a "prevlen" field of a since byte. This could happen when the
"cascading update" process called by ziplistInsert()/ziplistDelete() in
certain contitious forces the prevlen to be bigger than necessary in
order to avoid too much data moving around.

Once such an entry is generated, inserting a very small entry
immediately before it will result in a resizing of the ziplist for a
count smaller than the current ziplist length (which is a violation,
inserting code expects the ziplist to get bigger actually). So an FF
byte is inserted in a misplaced position. Moreover a realloc() is
performed with a count smaller than the ziplist current length so the
final bytes could be trashed as well.

SECURITY IMPLICATIONS:

Currently it looks like an attacker can only crash a Redis server by
providing specifically choosen commands. However a FF byte is written
and there are other memory operations that depend on a wrong count, so
even if it is not immediately apparent how to mount an attack in order
to execute code remotely, it is not impossible at all that this could be
done. Attacks always get better... and we did not spent enough time in
order to think how to exploit this issue, but security researchers
or malicious attackers could.
2017-02-01 15:03:18 +01:00
deps Remove Lua state reference from buffers in lua_cmsgpack. 2016-02-10 09:16:48 +01:00
src Ziplist: insertion bug under particular conditions fixed. 2017-02-01 15:03:18 +01:00
tests Test: Handle LOADING in restart_instance. 2016-01-25 15:21:57 +01:00
utils Update redis-cli help and the script to generate it. 2015-11-17 15:40:18 +01:00
.gitignore Cluster: nodes.conf added to git ignore list. 2014-10-08 09:12:43 +02:00
00-RELEASENOTES Removes more spuriousness from 3.0.7 2016-01-30 23:23:19 +02:00
BUGS Fix typo 2014-10-06 10:07:01 +02:00
CONTRIBUTING CONTRIBUTING updated. 2015-10-27 12:07:54 +01:00
COPYING update copyright year 2015-05-04 12:56:50 +02:00
INSTALL INSTALL now redirects the user to README 2012-02-05 09:38:41 +01:00
MANIFESTO Format to fit 80 columns 2013-02-08 12:11:06 -06:00
Makefile Fix `install` target on OSX (see #495) 2012-05-15 11:18:50 +02:00
README README section about make distclean reworded / extended. 2015-01-08 16:35:39 +01:00
redis.conf Redis.conf example: make clear user must pass its path as argument. 2015-10-15 12:46:17 +02:00
runtest Check available tcl versions 2013-01-24 09:25:47 +11:00
runtest-cluster Redis Cluster test framework skeleton. 2014-04-28 18:17:02 +02:00
runtest-sentinel Sentinel test files / directories layout improved. 2014-04-28 18:17:02 +02:00
sentinel.conf Fix sentinel.conf typo 2014-10-06 10:07:02 +02:00

README

Where to find complete Redis documentation?
-------------------------------------------

This README is just a fast "quick start" document. You can find more detailed
documentation at http://redis.io

Building Redis
--------------

Redis can be compiled and used on Linux, OSX, OpenBSD, NetBSD, FreeBSD.
We support big endian and little endian architectures.

It may compile on Solaris derived systems (for instance SmartOS) but our
support for this platform is "best effort" and Redis is not guaranteed to
work as well as in Linux, OSX, and *BSD there.

It is as simple as:

    % make

You can run a 32 bit Redis binary using:

    % make 32bit

After building Redis is a good idea to test it, using:

    % make test

Fixing build problems with dependencies or cached build options
—--------
Redis has some dependencies which are included into the "deps" directory.
"make" does not rebuild dependencies automatically, even if something in the
source code of dependencies is changes.

When you update the source code with `git pull` or when code inside the
dependencies tree is modified in any other way, make sure to use the following
command in order to really clean everything and rebuild from scratch:

    make distclean

This will clean: jemalloc, lua, hiredis, linenoise.

Also if you force certain build options like 32bit target, no C compiler
optimizations (for debugging purposes), and other similar build time options,
those options are cached indefinitely until you issue a "make distclean"
command.

Fixing problems building 32 bit binaries
---------

If after building Redis with a 32 bit target you need to rebuild it
with a 64 bit target, or the other way around, you need to perform a
"make distclean" in the root directory of the Redis distribution.

In case of build errors when trying to build a 32 bit binary of Redis, try
the following steps:

* Install the packages libc6-dev-i386 (also try g++-multilib).
* Try using the following command line instead of "make 32bit":

    make CFLAGS="-m32 -march=native" LDFLAGS="-m32"

Allocator
---------

Selecting a non-default memory allocator when building Redis is done by setting
the `MALLOC` environment variable. Redis is compiled and linked against libc
malloc by default, with the exception of jemalloc being the default on Linux
systems. This default was picked because jemalloc has proven to have fewer
fragmentation problems than libc malloc.

To force compiling against libc malloc, use:

    % make MALLOC=libc

To compile against jemalloc on Mac OS X systems, use:

    % make MALLOC=jemalloc

Verbose build
-------------

Redis will build with a user friendly colorized output by default.
If you want to see a more verbose output use the following:

    % make V=1

Running Redis
-------------

To run Redis with the default configuration just type:

    % cd src
    % ./redis-server
    
If you want to provide your redis.conf, you have to run it using an additional
parameter (the path of the configuration file):

    % cd src
    % ./redis-server /path/to/redis.conf

It is possible to alter the Redis configuration passing parameters directly
as options using the command line. Examples:

    % ./redis-server --port 9999 --slaveof 127.0.0.1 6379
    % ./redis-server /etc/redis/6379.conf --loglevel debug

All the options in redis.conf are also supported as options using the command
line, with exactly the same name.

Playing with Redis
------------------

You can use redis-cli to play with Redis. Start a redis-server instance,
then in another terminal try the following:

    % cd src
    % ./redis-cli
    redis> ping
    PONG
    redis> set foo bar
    OK
    redis> get foo
    "bar"
    redis> incr mycounter
    (integer) 1
    redis> incr mycounter
    (integer) 2
    redis> 

You can find the list of all the available commands here:

    http://redis.io/commands

Installing Redis
-----------------

In order to install Redis binaries into /usr/local/bin just use:

    % make install

You can use "make PREFIX=/some/other/directory install" if you wish to use a
different destination.

Make install will just install binaries in your system, but will not configure
init scripts and configuration files in the appropriate place. This is not
needed if you want just to play a bit with Redis, but if you are installing
it the proper way for a production system, we have a script doing this
for Ubuntu and Debian systems:

    % cd utils
    % ./install_server.sh

The script will ask you a few questions and will setup everything you need
to run Redis properly as a background daemon that will start again on
system reboots.

You'll be able to stop and start Redis using the script named
/etc/init.d/redis_<portnumber>, for instance /etc/init.d/redis_6379.

Code contributions
---

Note: by contributing code to the Redis project in any form, including sending
a pull request via Github, a code fragment or patch via private email or
public discussion groups, you agree to release your code under the terms
of the BSD license that you can find in the COPYING file included in the Redis
source distribution.

Please see the CONTRIBUTING file in this source distribution for more
information.

Enjoy!