[editing] Avoid ReplaceSelectionCommand crashes with mixed editability

Executing document.execCommand('InsertImage') with this HTML:

  <body contenteditable="true">
    <div contenteditable="false">
      <span contenteditable="true">a|b</span>

runs ReplaceSelectionCommand::InsertParagraphSeparatorIfNeeds().
This would typically split the <span> and insert the <img> as a child of
the <div>. However, the <div> is not editable, so a new <div> was added
at the end of the <body>, since it's an editable ancestor.

A DCHECK failed when collapsing the selection to the VisiblePosition in
the new <div> because the canonical position is null when the height of
a block is 0 (see IsVisuallyEquivalentCandidateAlgorithm).

Alternatively, we can modify the testcase a bit to trigger a null deref.
MergeEndIfNeeded() uses PositionAtEndOfInsertedContent(), which may be
a null VisiblePosition if the original Position couldn't be normalized.
Then it could call InsertNodeBefore() with a null node which would be

This patch avoids this kind of problems by making that code not skip
over non-editable ancestors in EnclosingBlock(). To do so, changes
EnclosingNodeOfTypeAlgorithm() to use RootEditableElementOf() instead
of HighestEditableRoot() when rule == kCannotCrossEditingBoundary.
The difference is that RootEditableElementOf() doesn't cross editing

Bug: 1246674


Change-Id: Icf93a26c6f1581fc1710a45128fe36d8860e5701
Cq-Do-Not-Cancel-Tryjobs: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3156666
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#920693}
5 files changed
tree: b56238c0e66df82b43cbea2467c7c0ba35c31394
  1. .clang-format
  2. .clang-tidy
  3. .eslintrc.js
  4. .git-blame-ignore-revs
  5. .gitattributes
  6. .gitignore
  7. .gn
  8. .mailmap
  9. .vpython
  10. .vpython3
  11. .yapfignore
  13. BUILD.gn
  15. DEPS
  19. LICENSE.chromium_os
  20. OWNERS
  21. PRESUBMIT.py
  22. PRESUBMIT_test.py
  23. PRESUBMIT_test_mocks.py
  24. README.md
  26. android_webview/
  27. apps/
  28. ash/
  29. base/
  30. build/
  31. build_overrides/
  32. buildtools/
  33. cc/
  34. chrome/
  35. chromecast/
  36. chromeos/
  37. cloud_print/
  38. codelabs/
  39. codereview.settings
  40. components/
  41. content/
  42. courgette/
  43. crypto/
  44. dbus/
  45. device/
  46. docs/
  47. extensions/
  48. fuchsia/
  49. gin/
  50. google_apis/
  51. google_update/
  52. gpu/
  53. headless/
  54. infra/
  55. ios/
  56. ipc/
  57. jingle/
  58. media/
  59. mojo/
  60. native_client_sdk/
  61. net/
  62. pdf/
  63. ppapi/
  64. printing/
  65. remoting/
  66. rlz/
  67. sandbox/
  68. services/
  69. skia/
  70. sql/
  71. storage/
  72. styleguide/
  73. testing/
  74. third_party/
  75. tools/
  76. ui/
  77. url/
  78. weblayer/

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