From: "kjtsanaktsidis (KJ Tsanaktsidis) via ruby-core" <ruby-core@...>
Date: 2023-12-20T04:13:52+00:00
Subject: [ruby-core:115799] [Ruby master Bug#20072] free(): invalid pointer when compiled with --enable-shared --with-jemalloc

Issue #20072 has been updated by kjtsanaktsidis (KJ Tsanaktsidis).


I wasn't able to reproduce your crash, but there is definitely a problem - when using `--enable-shared` and `--with-jemalloc` together, the Ruby that gets built still uses libc's malloc and ignores jemalloc. This is because we pass `-ljemalloc` to the link line for `libruby.so`, but we _don't_ pass it to `ruby`. This means that the built Ruby isn't marked as needing `libjemalloc.so`:

```
root@jammy-189dc9d584290f1a:/var/ruby# readelf --dynamic ruby | grep NEEDED
 0x0000000000000001 (NEEDED)             Shared library: [libruby.so.3.3]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]with
```

And because the dynamic linker (at lesat the glibc one) links libraries in breadth-first order, that means that `libc.so.6` is linked before `libjemalloc.so.2`:

```
root@jammy-189dc9d584290f1a:/var/ruby# ldd ruby
	linux-vdso.so.1 (0x00007ffe873fb000)
	libruby.so.3.3 => /usr/local/lib/libruby.so.3.3 (0x00007f8870000000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f886fc00000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f887054c000)
	libjemalloc.so.2 => /lib/x86_64-linux-gnu/libjemalloc.so.2 (0x00007f886f800000)
	libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007f8870512000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f886ff19000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f8870572000)
	libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f886f400000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f886fef9000)
```

We need to pass `-ljemalloc` to the linker command line for the final Ruby executable. I'm playing around trying to find the right Autoconf magic spells for this now.

----------------------------------------
Bug #20072: free(): invalid pointer when compiled with --enable-shared --with-jemalloc
https://bugs.ruby-lang.org/issues/20072#change-105745

* Author: misdoro (Mikhail Doronin)
* Status: Open
* Priority: Normal
* Target version: 3.3
* ruby -v: ruby 3.3.0dev (2023-08-17T01:57:09Z test 5bb9462285) [x86_64-linux] 
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
When ruby is built with `--enable-shared --with-jemalloc` on Linux (current Gentoo, ubuntu22 in docker),

running a rails app yields:
```
free(): invalid pointer
Aborted
```

The issue started appearing after 5bb946228550c7f171c27725860b153a675404f3 https://github.com/ruby/ruby/commit/5bb946228550c7f171c27725860b153a675404f3

Related to https://bugs.ruby-lang.org/issues/18409 (workaround to LD_PRELOAD jemalloc from that issue works)

---Files--------------------------------
config.log (1.34 MB)


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