[mythtv-commits] [MythTV/mythtv] 66ba83: MythEDID: fix out of bounds memory access

Scott Theisen noreply at github.com
Sat Jun 25 13:29:22 UTC 2022

  Branch: refs/heads/fixes/32
  Home:   https://github.com/MythTV/mythtv
  Commit: 66ba83839a20e7c9adf0347ab6963dcdf1a58e6e
  Author: Scott Theisen <scott.the.elm at gmail.com>
  Date:   2022-06-25 (Sat, 25 Jun 2022)

  Changed paths:
    M mythtv/libs/libmythui/mythedid.cpp

  Log Message:
  MythEDID: fix out of bounds memory access

found by valgrind while investigating segmentation faults that
occured randomly on startup of mythfrontend.

There are only 4 descriptors in the EDID data structure.
By incorrectly looping 5 times in MythEDID::ParseBaseBlock(),
an offset of 126 is passed to ParseDisplayDescriptor() or
ParseDetailedTimingDescriptor() which will then read past
the end of the 128 byte EDID data structure.

This appears to have always been wrong since it was added in
53d170221983764ae108939cbdb0bcbfc48b6114 .

(cherry picked from commit 8e36123478cb98f0134bdc4447beb51d8e708385)

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