realloc returns memory overlapping with other memory block

[mrk-its]

Following rust program day05.zip crashes because of heap memory corruption.

I'm attaching small python script with sequence of malloc / realloc / free calls logged from above program, looking for block overlaps. It looks that one of the realloc calls returns region overlapping with other block allocated earlier (probably because of https://github.com/llvm-mos/llvm-mos-sdk/pull/292)

Replacing realloc with alloc + memcpy makes this program working fine. It also works fine on older SDK with previous malloc implementation.

[mysterymath]

Thanks, I expected that something would break after a big malloc rewrite; looks like this is it. I'll go through and debug this.

[mysterymath]

Nothing immediately jumps out at me as incorrect in realloc; the issue may be subtle.

Could you make a .ll version of this that I could compile against a different version of malloc? I've got a bunch of tracing in the SDK that would be very helpful.

Failing that, the output of this recompiled against an SDK with MALLOC_TRACE set to 1 inmalloc.cc might be enough, but it's worse than being able to add printing on my end.

[mrk-its]

Debug build: day05-0cd8b2583aaf17c6.zip

Release build: day05-fa63e06c3e659ee6.zip

It was produced by llvm-mos: 1d7989f29 and sdk: 777e89e