Fix null-dereference READ in AXPosition::AsValidDOMPosition

This is a follow-up to http://crrev.com/c/2426490 which prevents an
infinite loop in AXPosition::AsValidDOMPosition by ensuring we have
a changed AXPosition after calling CreatePreviousPosition in generated
content. That fix failed to check that the previous position created
was not null prior to seeing if it had indeed changed.

Bugs: 1131019, 1133124

AX-Relnotes: Prevents a page crash when accessibility is enabled.
Change-Id: Iaa8a7d79c5750809e6a3d39f7077f6593f95488d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2440630
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812793}
4 files changed
tree: 88bc9c0e54eaf0481d9e2b2ed42d422b1069b05f
  1. .clang-format
  2. .clang-tidy
  3. .eslintrc.js
  4. .git-blame-ignore-revs
  5. .gitattributes
  6. .gitignore
  7. .gn
  8. .vpython
  9. .vpython3
  10. .yapfignore
  11. AUTHORS
  12. BUILD.gn
  13. CODE_OF_CONDUCT.md
  14. DEPS
  15. DIR_METADATA
  16. ENG_REVIEW_OWNERS
  17. LICENSE
  18. LICENSE.chromium_os
  19. OWNERS
  20. PRESUBMIT.py
  21. PRESUBMIT_test.py
  22. PRESUBMIT_test_mocks.py
  23. README.md
  24. WATCHLISTS
  25. android_webview/
  26. apps/
  27. ash/
  28. base/
  29. build/
  30. build_overrides/
  31. buildtools/
  32. cc/
  33. chrome/
  34. chromecast/
  35. chromeos/
  36. cloud_print/
  37. codereview.settings
  38. components/
  39. content/
  40. courgette/
  41. crypto/
  42. dbus/
  43. device/
  44. docs/
  45. extensions/
  46. fuchsia/
  47. gin/
  48. google_apis/
  49. google_update/
  50. gpu/
  51. headless/
  52. infra/
  53. ios/
  54. ipc/
  55. jingle/
  56. media/
  57. mojo/
  58. native_client_sdk/
  59. net/
  60. pdf/
  61. ppapi/
  62. printing/
  63. remoting/
  64. rlz/
  65. sandbox/
  66. services/
  67. skia/
  68. sql/
  69. storage/
  70. styleguide/
  71. testing/
  72. third_party/
  73. tools/
  74. ui/
  75. url/
  76. weblayer/
README.md

Logo Chromium

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