Bug #20072: free(): invalid pointer when compiled with --enable-shared --with-jemalloc

• Status: Closed
• Assignee: -
• 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

[misdoro (Mikhail Doronin)]

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)

[nobu (Nobuyoshi Nakada)]

Could you share your config.log and crash report?

[hsbt (Hiroshi SHIBATA)]

• Target version set to 3.3

[misdoro (Mikhail Doronin)]

• File config.log added

Hi Nobu, you will find the config.log attached.

Debugged it a bit deeper, it boils down to:

• install ruby with --enable-shared --with-jemalloc
• gem install sassc
• running irb and require 'sassc'
  that is immediately crashing:

$ irb
irb(main):001> require 'sassc'
free(): invalid pointer
Aborted

[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]

And because the dynamic linker (at least 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.

[hsbt (Hiroshi SHIBATA)]

• Related to Bug #19831: warning message of linker with macOS Sonoma beta added

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Closed

https://github.com/ruby/ruby/pull/9284 has been merged.

#19831 is already solved. There are no warnings with the latest Xcode.

[shyouhei (Shyouhei Urabe)]

This issue reminds me of https://github.com/ruby/ruby/pull/4627

[misdoro (Mikhail Doronin)]

• File deleted (config.log)