Coredump at sdscatlen

[mayursankpal]

Hiredis version = 0.11.0
OS = Debian GNU/Linux 11 (bullseye)
Redis server v=6.0.16 sha=00000000:0 malloc=jemalloc-5.2.1 bits=64 build=6d95e1af3a2c082a

Scenario ==> Inserting data into redis DB ...Called from one of the unit test [googletest]
Command ==> "HSET <some_key> state off"

Stack Trace
Program received signal SIGSEGV, Segmentation fault.
__redisAppendCommand (c=0x0,
cmd=0x4daf10 "*4\r\n$4\r\nHSET\r\n$20\r\nsome_key\r\n$5\r\nstate\r\n$3\r\noff\r\n", len=61)
at hiredis.c:1186
1186 newbuf = sdscatlen(c->obuf,cmd,len);
(gdb) bt
#0 __redisAppendCommand (c=0x0,
cmd=0x4daf10 "*4\r\n$4\r\nHSET\r\n$20\r\nsome_key\r\n$5\r\nstate\r\n$3\r\noff\r\n", len=61)
at hiredis.c:1186
#1 0x00007fffff6f461c in redisvAppendCommand (c=0x0, format=, ap=) at hiredis.c:1206
#2 0x00007fffff6f4792 in redisvCommand (c=0x0, format=, ap=ap@entry=0x7ffffffed498) at hiredis.c:1267
#3 0x00007fffff6f4847 in redisCommand (c=,
format=format@entry=0x4dc530 "HSET runtime.status.comms state off") at hiredis.c:1276

[michael-grunder]

Looks like you aren't making redisConnect is returning a valid context as c=0x0.

So you've got a NULL redisContext making redisContext->obuf just 0 + the offset of that member, which if course is not a valid sds string 😄

I can't help much more than that without a bit of code that reproduces the issue. Fix should be simple though. Just make sure redisConnect is returning a valid pointer and c->err is not set.

[michael-grunder]

Closing as this doesn't seem to be a bug in hiredis but still happy to answer any other questions you have.