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Bug #17552

[PATCH] Fix a NULL pointer crash in ObjectSpace.dump_all

Added by byroot (Jean Boussier) about 1 month ago. Updated 29 days ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Target version:
-
ruby -v:
ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-darwin19]
[ruby-core:102133]

Description

Patch: https://github.com/ruby/ruby/pull/4078

I wasn't able to reproduce the issue in isolation just yet, but I confirmed the patch fixes the issue for us.

What seem to happen in that some objects have an allocation_info, but allocation_info->path == NULL.

What is weird is that in 2.7.2, there was no NULL check for ->path, it was directly passed to vfprintf, which from what I understand would have generated "path": (null), which is invalid JSON.
So I suspect allocation_info { path = NULL } wasn't possible on 2.7.2?

Either way I'd like to write a test case for this, but I'm still unable to find a way to create an object with a NULL path.

Updated by byroot (Jean Boussier) about 1 month ago

So with some extra debug code, I've managed to identify the object that causes this, it's only one object on a multi-GiB dump:

{"address":"0x7f32c8b8d6c8", "type":"IMEMO", "class":"0x8", "imemo_type":"ment", "generation":57, "memsize":48, "flags":{"wb_protected":true, "old":true, "uncollectible":true, "marked":true}}

I don't know wether this is expected or not, the "class":"0x8" is particularly surprising.

Updated by tenderlovemaking (Aaron Patterson) about 1 month ago

  • Backport changed from 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN to 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: REQUIRED
  • Status changed from Open to Closed

This is fixed in 6ca3d1af3302f722aed530764d07c1cc83e95ecf

Updated by naruse (Yui NARUSE) 29 days ago

  • Backport changed from 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: REQUIRED to 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: DONE

ruby_3_0 06da90a146346d6968a8716a9035ede7104c0f97 merged revision(s) 6ca3d1af3302f722aed530764d07c1cc83e95ecf.

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