[Bug]: Large amount of invisible unicode characters causes freeze and crash #3839
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tstein
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Feb 16, 2024
This prevents the crash in termux#3839, but not by enough to call it done. Termux gets stuck on the very bad line and is responsive, but laggy enough to trigger ANRs. It's possible to ^C in this state and get your terminal back with no apparent damage.
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Sent #3840 with a fix for the crash, but there's still something asymptotically disastrous going on here. I gave it 15+ minutes trying to print the bad line before ^C. |
agnostic-apollo
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Mar 21, 2024
… to prevent buffer overflows The exception below causing app crash happens because of malicious input where combining characters keep getting added to same column of the row and this increases the size of `mSpaceUsed` and `mText`, eventually causing a buffer overflow of `mSpaceUsed`, which is limited to max `32767` value as per java `short` limit, but the limit itself isn't the issue, but an endless number of combining characters being added. Check `MAX_COMBINING_CHARACTERS_PER_COLUMN` field javadocs for why the limit `15` was chosen. ``` curl -o matroska.js https://kimapr.net/lappy/matroska.js cat matroska.js ``` The `charCount` below refers to value of `Character.charCount(codePoint)`, like before `oldCharactersUsedForColumn` is appended to `newCharactersUsedForColumn`. ``` TerminalRow: codePoint=112, mColumns=98, mText=637, columnToSet=18, mSpaceUsed=590, javaCharDifference=0, oldStartOfColumnIndex=510, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=1, oldNextColumnIndex=511, newNextColumnIndex=511, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=1 TerminalRow: codePoint=40, mColumns=98, mText=637, columnToSet=19, mSpaceUsed=590, javaCharDifference=0, oldStartOfColumnIndex=511, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=1, oldNextColumnIndex=512, newNextColumnIndex=512, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=1 TerminalRow: codePoint=40, mColumns=98, mText=637, columnToSet=20, mSpaceUsed=590, javaCharDifference=0, oldStartOfColumnIndex=512, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=1, oldNextColumnIndex=513, newNextColumnIndex=513, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=1 TerminalRow: codePoint=101, mColumns=98, mText=637, columnToSet=21, mSpaceUsed=590, javaCharDifference=0, oldStartOfColumnIndex=513, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=1, oldNextColumnIndex=514, newNextColumnIndex=514, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=1 TerminalRow: codePoint=917772, mColumns=98, mText=147, columnToSet=18, mSpaceUsed=98, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=3, oldNextColumnIndex=19, newNextColumnIndex=21, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 I TerminalRow: codePoint=65024, mColumns=98, mText=147, columnToSet=18, mSpaceUsed=100, javaCharDifference=1, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=3, newCharactersUsedForColumn=4, oldNextColumnIndex=21, newNextColumnIndex=22, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 TerminalRow: codePoint=917772, mColumns=98, mText=147, columnToSet=18, mSpaceUsed=101, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=4, newCharactersUsedForColumn=6, oldNextColumnIndex=22, newNextColumnIndex=24, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 ... TerminalRow: codePoint=917959, mColumns=98, mText=32781, columnToSet=18, mSpaceUsed=32763, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=32666, newCharactersUsedForColumn=32668, oldNextColumnIndex=32684, newNextColumnIndex=32686, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 TerminalRow: codePoint=917939, mColumns=98, mText=32781, columnToSet=18, mSpaceUsed=32765, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=32668, newCharactersUsedForColumn=32670, oldNextColumnIndex=32686, newNextColumnIndex=32688, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 TerminalRow: codePoint=917961, mColumns=98, mText=32781, columnToSet=18, mSpaceUsed=32767, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=32670, newCharactersUsedForColumn=32672, oldNextColumnIndex=32688, newNextColumnIndex=32690, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 TerminalRow: codePoint=917804, mColumns=98, mText=32781, columnToSet=18, mSpaceUsed=-32767, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=3, oldNextColumnIndex=19, newNextColumnIndex=21, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 ``` ``` java.lang.ArrayIndexOutOfBoundsException: src.length=32781 srcPos=19 dst.length=32781 dstPos=21 length=-32786 at java.lang.System.arraycopy(System.java:469) at com.termux.terminal.TerminalRow.setChar(TerminalRow.java:196) at com.termux.terminal.TerminalBuffer.setChar(TerminalBuffer.java:455) at com.termux.terminal.TerminalEmulator.emitCodePoint(TerminalEmulator.java:2380) at com.termux.terminal.TerminalEmulator.processCodePoint(TerminalEmulator.java:624) at com.termux.terminal.TerminalEmulator.processByte(TerminalEmulator.java:520) at com.termux.terminal.TerminalEmulator.append(TerminalEmulator.java:487) at com.termux.terminal.TerminalSession$MainThreadHandler.handleMessage(TerminalSession.java:358) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:223) at android.app.ActivityThread.main(ActivityThread.java:7664) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) ``` See also following links for history of related changes to `TerminalRow` for combining characters. Note that jackpal terminal does not crash for above, which termux-app is based on, but changes were done by fornwall in initial commit of termux-app to change the behaviour, hence the crash, but he added the `FIXME: Put a limit of combining characters` comment as a note to solve the current issue in future, which is now. - jackpal/Android-Terminal-Emulator@9a47042 - jackpal/Android-Terminal-Emulator#338 - termux@a18ee58#diff-f84d215b18106c037e01986a3968fa54b74691174a78fcc99493f745d3805be5 Closes termux#3839
agnostic-apollo
added a commit
to tstein/termux-app
that referenced
this issue
Apr 7, 2024
… to prevent buffer overflows The exception below causing app crash happens because of malicious input where combining characters keep getting added to same column of the row and this increases the size of `mSpaceUsed` and `mText`, eventually causing a buffer overflow of `mSpaceUsed`, which is limited to max `32767` value as per java `short` limit, but the limit itself isn't the issue, but an endless number of combining characters being added. Check `MAX_COMBINING_CHARACTERS_PER_COLUMN` field javadocs for why the limit `15` was chosen. ``` curl -o matroska.js https://kimapr.net/lappy/matroska.js cat matroska.js ``` The `charCount` below refers to value of `Character.charCount(codePoint)`, like before `oldCharactersUsedForColumn` is appended to `newCharactersUsedForColumn`. ``` TerminalRow: codePoint=112, mColumns=98, mText=637, columnToSet=18, mSpaceUsed=590, javaCharDifference=0, oldStartOfColumnIndex=510, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=1, oldNextColumnIndex=511, newNextColumnIndex=511, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=1 TerminalRow: codePoint=40, mColumns=98, mText=637, columnToSet=19, mSpaceUsed=590, javaCharDifference=0, oldStartOfColumnIndex=511, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=1, oldNextColumnIndex=512, newNextColumnIndex=512, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=1 TerminalRow: codePoint=40, mColumns=98, mText=637, columnToSet=20, mSpaceUsed=590, javaCharDifference=0, oldStartOfColumnIndex=512, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=1, oldNextColumnIndex=513, newNextColumnIndex=513, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=1 TerminalRow: codePoint=101, mColumns=98, mText=637, columnToSet=21, mSpaceUsed=590, javaCharDifference=0, oldStartOfColumnIndex=513, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=1, oldNextColumnIndex=514, newNextColumnIndex=514, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=1 TerminalRow: codePoint=917772, mColumns=98, mText=147, columnToSet=18, mSpaceUsed=98, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=3, oldNextColumnIndex=19, newNextColumnIndex=21, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 I TerminalRow: codePoint=65024, mColumns=98, mText=147, columnToSet=18, mSpaceUsed=100, javaCharDifference=1, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=3, newCharactersUsedForColumn=4, oldNextColumnIndex=21, newNextColumnIndex=22, charCount=1, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 TerminalRow: codePoint=917772, mColumns=98, mText=147, columnToSet=18, mSpaceUsed=101, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=4, newCharactersUsedForColumn=6, oldNextColumnIndex=22, newNextColumnIndex=24, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 ... TerminalRow: codePoint=917959, mColumns=98, mText=32781, columnToSet=18, mSpaceUsed=32763, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=32666, newCharactersUsedForColumn=32668, oldNextColumnIndex=32684, newNextColumnIndex=32686, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 TerminalRow: codePoint=917939, mColumns=98, mText=32781, columnToSet=18, mSpaceUsed=32765, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=32668, newCharactersUsedForColumn=32670, oldNextColumnIndex=32686, newNextColumnIndex=32688, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 TerminalRow: codePoint=917961, mColumns=98, mText=32781, columnToSet=18, mSpaceUsed=32767, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=32670, newCharactersUsedForColumn=32672, oldNextColumnIndex=32688, newNextColumnIndex=32690, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 TerminalRow: codePoint=917804, mColumns=98, mText=32781, columnToSet=18, mSpaceUsed=-32767, javaCharDifference=2, oldStartOfColumnIndex=18, oldCharactersUsedForColumn=1, newCharactersUsedForColumn=3, oldNextColumnIndex=19, newNextColumnIndex=21, charCount=2, oldCodePointDisplayWidth=1, newCodePointDisplayWidth=0 ``` ``` java.lang.ArrayIndexOutOfBoundsException: src.length=32781 srcPos=19 dst.length=32781 dstPos=21 length=-32786 at java.lang.System.arraycopy(System.java:469) at com.termux.terminal.TerminalRow.setChar(TerminalRow.java:196) at com.termux.terminal.TerminalBuffer.setChar(TerminalBuffer.java:455) at com.termux.terminal.TerminalEmulator.emitCodePoint(TerminalEmulator.java:2380) at com.termux.terminal.TerminalEmulator.processCodePoint(TerminalEmulator.java:624) at com.termux.terminal.TerminalEmulator.processByte(TerminalEmulator.java:520) at com.termux.terminal.TerminalEmulator.append(TerminalEmulator.java:487) at com.termux.terminal.TerminalSession$MainThreadHandler.handleMessage(TerminalSession.java:358) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:223) at android.app.ActivityThread.main(ActivityThread.java:7664) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) ``` See also following links for history of related changes to `TerminalRow` for combining characters. Note that jackpal terminal does not crash for above, which termux-app is based on, but changes were done by fornwall in initial commit of termux-app to change the behaviour, hence the crash, but he added the `FIXME: Put a limit of combining characters` comment as a note to solve the current issue in future, which is now. - jackpal/Android-Terminal-Emulator@9a47042 - jackpal/Android-Terminal-Emulator#338 - termux@a18ee58#diff-f84d215b18106c037e01986a3968fa54b74691174a78fcc99493f745d3805be5 Closes termux#3839
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Problem description
Printing a specific file to terminal freezes and crashes Termux. The file is valid UTF-8 but contains large amounts of various invisible Unicode characters, including zero-width spaces, word joiners, variant selectors, etc.
Steps to reproduce the behavior.
cator similarWhat is the expected behavior?
Termux does not freeze or crash
System information
The text was updated successfully, but these errors were encountered: