- 20 Feb, 2017 5 commits
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antirez authored
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antirez authored
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antirez authored
This change attempts to switch to an hash function which mitigates the effects of the HashDoS attack (denial of service attack trying to force data structures to worst case behavior) while at the same time providing Redis with an hash function that does not expect the input data to be word aligned, a condition no longer true now that sds.c strings have a varialbe length header. Note that it is possible sometimes that even using an hash function for which collisions cannot be generated without knowing the seed, special implementation details or the exposure of the seed in an indirect way (for example the ability to add elements to a Set and check the return in which Redis returns them with SMEMBERS) may make the attacker's life simpler in the process of trying to guess the correct seed, however the next step would be to switch to a log(N) data structure when too many items in a single bucket are detected: this seems like an overkill in the case of Redis. SPEED REGRESION TESTS: In order to verify that switching from MurmurHash to SipHash had no impact on speed, a set of benchmarks involving fast insertion of 5 million of keys were performed. The result shows Redis with SipHash in high pipelining conditions to be about 4% slower compared to using the previous hash function. However this could partially be related to the fact that the current implementation does not attempt to hash whole words at a time but reads single bytes, in order to have an output which is endian-netural and at the same time working on systems where unaligned memory accesses are a problem. Further X86 specific optimizations should be tested, the function may easily get at the same level of MurMurHash2 if a few optimizations are performed.
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John.Koepi authored
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antirez authored
Close #3804.
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- 09 Feb, 2017 1 commit
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antirez authored
After investigating issue #3796, it was discovered that MIGRATE could call migrateCloseSocket() after the original MIGRATE c->argv was already rewritten as a DEL operation. As a result the host/port passed to migrateCloseSocket() could be anything, often a NULL pointer that gets deferenced crashing the server. Now the socket is closed at an earlier time when there is a socket error in a later stage where no retry will be performed, before we rewrite the argument vector. Moreover a check was added so that later, in the socket_err label, there is no further attempt at closing the socket if the argument was rewritten. This fix should resolve the bug reported in #3796.
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- 01 Feb, 2017 2 commits
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antirez authored
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antirez authored
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.
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- 30 Jan, 2017 1 commit
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antirez authored
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- 27 Jan, 2017 1 commit
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Jan-Erik Rediger authored
Previously Redis crashed on `MEMORY DOCTOR` when it has no slaves attached. Fixes #3783
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- 26 Jan, 2017 1 commit
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miter authored
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- 18 Jan, 2017 2 commits
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antirez authored
This header file is for libs, like ziplist.c, that we want to leave almost separted from the core. The panic() calls will be easy to delete in order to use such files outside, but the debugging info we gain are very valuable compared to simple assertions where it is not possible to print debugging info.
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antirez authored
This is of great interest because allows us to print debugging informations that could be of useful when debugging, like in the following example: serverPanic("Unexpected encoding for object %d, %d", obj->type, obj->encoding);
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- 13 Jan, 2017 1 commit
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antirez authored
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- 12 Jan, 2017 3 commits
- 11 Jan, 2017 3 commits
- 10 Jan, 2017 2 commits
- 08 Jan, 2017 1 commit
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Jan-Erik Rediger authored
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- 02 Jan, 2017 1 commit
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oranagra authored
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- 30 Dec, 2016 1 commit
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oranagra authored
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- 24 Dec, 2016 1 commit
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oranagra authored
getExpire calls dictFind which can do rehashing. found by calling computeDatasetDigest from serverCron and running the test suite.
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- 20 Dec, 2016 2 commits
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antirez authored
The same thing observed in #3551 by gnethercutt also fixed for GEOHASH as the original PR did.
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antirez authored
There were two cases outlined in issue #3512 and PR #3551 where the Geo API returned unexpected results: empty strings where NULL replies were expected, or a single null reply where an array was expected. This violates the Redis principle that Redis replies for existing keys or elements should be indistinguishable. This is technically an API breakage so will be merged only into 4.0 and specified in the changelog in the list of breaking compatibilities, even if it is not very likely that actual code will be affected, hopefully, since with the past behavior basically there was to acconut for *both* the possibilities, and the new behavior is always one of the two, but in a consistent way.
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- 19 Dec, 2016 4 commits
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Justin Carvalho authored
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antirez authored
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antirez authored
You can still force the logo in the normal logs. For motivations, check issue #3112. For me the reason is that actually the logo is nice to have in interactive sessions, but inside the logs kinda loses its usefulness, but for the ability of users to recognize restarts easily: for this reason the new startup sequence shows a one liner ASCII "wave" so that there is still a bit of visual clue. Startup logging was modified in order to log events in more obvious ways, and to log more events. Also certain important informations are now more easy to parse/grep since they are printed in field=value style. The option --always-show-logo in redis.conf was added, defaulting to no.
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antirez authored
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- 16 Dec, 2016 6 commits
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antirez authored
This commit also contains other changes in order to conform the code to the Redis core style, specifically 80 chars max per line, smart conditionals in the same line: if (that) do_this();
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antirez authored
The new algorithm provides the same speed with a smaller error for cardinalities in the range 0-100k. Before switching, the new and old algorithm behavior was studied in details in the context of issue #3677. You can find a few graphs and motivations there.
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antirez authored
Otherwise for small cardinalities the algorithm will output something like, for example, 4.99 for a candinality of 5, that will be converted to 4 producing a huge error.
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Harish Murthy authored
Config option to use LogLog-Beta Algorithm for Cardinality
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antirez authored
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antirez authored
The commit improves ziplistRepr() and adds a new debugging subcommand so that we can trigger the dump directly from the Redis API. This command capability was used while investigating issue #3684.
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- 14 Dec, 2016 2 commits