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Bug #19469

closed

Crash when resizing generic iv list

Added by peterzhu2118 (Peter Zhu) over 1 year ago. Updated over 1 year ago.

Status:
Closed
Assignee:
-
Target version:
-
[ruby-core:112634]

Description

GitHub PR: https://github.com/ruby/ruby/pull/7407

The following script can sometimes trigger a crash:

GC.stress = true

class Array
  def foo(bool)
    if bool
      @a = 1
      @b = 2
      @c = 1
    else
      @c = 1
    end
  end
end

obj = []
obj.foo(true)

obj2 = []
obj2.foo(false)

obj3 = []
obj3.foo(true)

This is because vm_setivar_default calls rb_ensure_generic_iv_list_size to resize the iv list. However, the call to gen_ivtbl_resize reallocs the iv list, and then inserts into the generic iv table. If the st_insert triggers a GC then the old iv list will be read during marking, causing a use-after-free bug.


Related issues 2 (0 open2 closed)

Related to Ruby master - Bug #19477: segfault during GC if ivars set on arraysClosedtenderlovemaking (Aaron Patterson)Actions
Related to Ruby master - Bug #19433: Segmentation fault in 3.2.0/3.2.1 on M1 MacClosedActions

Updated by alanwu (Alan Wu) over 1 year ago

Could this be the cause of #19433?
The stack traces seem to indicate generic IV table resizing.

Actions #2

Updated by peterzhu2118 (Peter Zhu) over 1 year ago

  • Status changed from Open to Closed

Applied in changeset git|62c2082f1f726cb90d8c332fbedbecf41d5d82ec.


[Bug #19469] Fix crash when resizing generic iv list

The following script can sometimes trigger a crash:

GC.stress = true

class Array
  def foo(bool)
    if bool
      @a = 1
      @b = 2
      @c = 1
    else
      @c = 1
    end
  end
end

obj = []
obj.foo(true)

obj2 = []
obj2.foo(false)

obj3 = []
obj3.foo(true)

This is because vm_setivar_default calls rb_ensure_generic_iv_list_size
to resize the iv list. However, the call to gen_ivtbl_resize reallocs
the iv list, and then inserts into the generic iv table. If the
st_insert triggers a GC then the old iv list will be read during
marking, causing a use-after-free bug.

Co-Authored-By: Jemma Issroff

Actions #3

Updated by byroot (Jean Boussier) over 1 year ago

  • Related to Bug #19477: segfault during GC if ivars set on arrays added
Actions #4

Updated by peterzhu2118 (Peter Zhu) over 1 year ago

  • Related to Bug #19433: Segmentation fault in 3.2.0/3.2.1 on M1 Mac added

Updated by naruse (Yui NARUSE) over 1 year ago

  • Backport changed from 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: REQUIRED to 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONE

ruby_3_2 f3abe5ba645839fb2a686aee18d3466b59256af0 merged revision(s) 0700d0fd1c77b4fddf803dea3c10be654df600ff,62c2082f1f726cb90d8c332fbedbecf41d5d82ec.

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