After the first fix to the struct package I found another similar
problem, which is fixed by this patch. It could be reproduced easily by
running the following script:
return struct.unpack('f', "xxxxxxxxxxxxx",-3)
The above will access bytes before the 'data' pointer.
@soloestoy sent me this additional fixes, after searching for similar
problems to the one reported in mp_pack(). I'm committing the changes
because it was not possible during to make a public PR to protect Redis
users and give Redis providers some time to patch their systems.
During an auditing Apple found that the "struct" Lua package
we ship with Redis (http://www.inf.puc-rio.br/~roberto/struct/) contains
a security problem. A bound-checking statement fails because of integer
overflow. The bug exists since we initially integrated this package with
Lua, when scripting was introduced, so every version of Redis with
EVAL/EVALSHA capabilities exposed is affected.
Instead of just fixing the bug, the library was updated to the latest
version shipped by the author.
During an auditing effort, the Apple Vulnerability Research team discovered
a critical Redis security issue affecting the Lua scripting part of Redis.
-- Description of the problem
Several years ago I merged a pull request including many small changes at
the Lua MsgPack library (that originally I authored myself). The Pull
Request entered Redis in commit 90b6337c1, in 2014.
Unfortunately one of the changes included a variadic Lua function that
lacked the check for the available Lua C stack. As a result, calling the
"pack" MsgPack library function with a large number of arguments, results
into pushing into the Lua C stack a number of new values proportional to
the number of arguments the function was called with. The pushed values,
moreover, are controlled by untrusted user input.
This in turn causes stack smashing which we believe to be exploitable,
while not very deterministic, but it is likely that an exploit could be
created targeting specific versions of Redis executables. However at its
minimum the issue results in a DoS, crashing the Redis server.
-- Versions affected
Versions greater or equal to Redis 2.8.18 are affected.
-- Reproducing
Reproduce with this (based on the original reproduction script by
Apple security team):
https://gist.github.com/antirez/82445fcbea6d9b19f97014cc6cc79f8a
-- Verification of the fix
The fix was tested in the following way:
1) I checked that the problem is no longer observable running the trigger.
2) The Lua code was analyzed to understand the stack semantics, and that
actually enough stack is allocated in all the cases of mp_pack() calls.
3) The mp_pack() function was modified in order to show exactly what items
in the stack were being set, to make sure that there is no silent overflow
even after the fix.
-- Credits
Thank you to the Apple team and to the other persons that helped me
checking the patch and coordinating this communication.
Main reasons for upgrade:
- Remove a warning when building Redis
- Add multi pack/unpack
- Improve memory usage and use Lua allocator properly
- Fix some edge case encoding/decoding bugs
cjson calls isinf, but some Solaris versions don't have isinf
even with the attempted fix we have in deps/Makefile.
We can harmlessly include the Redis solarisfixes.h header to
give cjson proper isinf.
Note: cjson has a compile-time setting for using their own defined
isinf, but the Redis definition in solarisfixes.h is more complete.
Fixes antirez#1620
The new cjson has some improvements over our current version including
increased platform compatability, a new resource limit to restrict
decode depth, and better invalid number handling.
One minor change was required to deps/Makefile because this version
of cjson doesn't export itself globally, so we added a quick little
define of -DENABLE_CJSON_GLOBAL.
cjson now has an optional higher performing float parsing interface,
but we are not including it (g_fmt.c, dtoa.c) because it requires
endianness declaration during compile time.
This commit is exactly lua_cjson.c from 2.1.0 with one minor
change of altering the two Lua includes for local search
instead of system-wide importing.
A few people have written custom C commands because bit
manipulation isn't exposed through Lua. Let's give
them Mike Pall's bitop.
This adds bitop 1.0.2 (2012-05-08) from http://bitop.luajit.org/
bitop is imported as "bit" into the global namespace.
New Lua commands: bit.tobit, bit.tohex, bit.bnot, bit.band, bit.bor, bit.bxor,
bit.lshift, bit.rshift, bit.arshift, bit.rol, bit.ror, bit.bswap
Verification of working (the asserts would abort on error, so (nil) is correct):
127.0.0.1:6379> eval "assert(bit.tobit(1) == 1); assert(bit.band(1) == 1); assert(bit.bxor(1,2) == 3); assert(bit.bor(1,2,4,8,16,32,64,128) == 255)" 0
(nil)
127.0.0.1:6379> eval 'assert(0x7fffffff == 2147483647, "broken hex literals"); assert(0xffffffff == -1 or 0xffffffff == 2^32-1, "broken hex literals"); assert(tostring(-1) == "-1", "broken tostring()"); assert(tostring(0xffffffff) == "-1" or tostring(0xffffffff) == "4294967295", "broken tostring()")' 0
(nil)
Tests also integrated into the scripting tests and can be run with:
./runtest --single unit/scripting
Tests are excerpted from `bittest.lua` included in the bitop distribution.
There was a bug in the previous version of this library that caused a
crash under the circumstances described in issue #901.
The newer version of the library appears to be fixed (I tested it
manually with valgrind and everything seems fine now).
For more information about this library please visit this web site:
http://www.inf.puc-rio.br/~roberto/struct/
