Segmentation fault when toggling threads visibility while paused

[SpaghettiBorgar]

Making process threads visible while process updates are paused causes a crash if tree view is enabled.
Other permutations of the steps seems to result in the same issue.

Version: 3.4.0-dev-3.3.0-179-g59578af
Linux arch 6.10.2-zen1-1-zen #1 ZEN SMP PREEMPT_DYNAMIC Sat, 27 Jul 2024 16:49:32 +0000 x86_64 GNU/Linux

Steps to reproduce:

1. make sure process threads are hidden
2. Open tree view (F5)
3. Pause process updates (Shift+Z)
4. Show process threads (Shift+H)

Backtrace information:
----------------------
 0: 0x59ae5f4116a8  ./htop  (CRT_handleSIGSEGV+0xf6)  [0x59ae5f4116a8]
 1: 0x708ab81691d0  /usr/lib/libc.so.6  (+0)  [0x708ab81691cf]  {signal frame}
 2: 0x59ae5f418f86  ./htop  (Object_isA+0x12)  [0x59ae5f418f86]
 3: 0x59ae5f428aec  ./htop  (Vector_get+0x2a)  [0x59ae5f428aec]
 4: 0x59ae5f427838  ./htop  (Table_rebuildPanel+0xc2)  [0x59ae5f427838]
 5: 0x59ae5f421ee9  ./htop  (checkRecalculation+0x138)  [0x59ae5f421ee9]
 6: 0x59ae5f42265f  ./htop  (ScreenManager_run+0xba)  [0x59ae5f42265f]
 7: 0x59ae5f40f74e  ./htop  (CommandLine_run+0x2e3)  [0x59ae5f40f74e]
 8: 0x59ae5f40ad42  ./htop  (main+0x9)  [0x59ae5f40ad42]
 9: 0x708ab8151e08  /usr/lib/libc.so.6  (+0)  [0x708ab8151d90]
10: 0x708ab8151ecc  /usr/lib/libc.so.6  (__libc_start_main+0x8c)  [0x708ab8151ecc]
11: 0x59ae5f40ac65  ./htop  (_start+0x25)  [0x59ae5f40ac65]

[natoscott]

I poked at it for awhile but haven't been able to get to the root cause so far. Valgrind suggests it relates to a process/thread that has been deleted (exited) and is removed from the Table hash but still exists in the displayList somehow.

==3122235== Invalid read of size 8
==3122235==    at 0x42B004: Table_rebuildPanel (Table.c:258)
==3122235==    by 0x42592B: checkRecalculation (ScreenManager.c:156)
==3122235==    by 0x42613B: ScreenManager_run (ScreenManager.c:247)
==3122235==    by 0x4154B7: CommandLine_run (CommandLine.c:407)
==3122235==    by 0x410CF7: main (htop.c:17)
==3122235==  Address 0x1330f040 is 0 bytes inside a block of size 808 free'd
==3122235==    at 0x48C3AAC: free (vg_replace_malloc.c:989)
==3122235==    by 0x430BDF: Process_delete (LinuxProcess.c:134)
==3122235==    by 0x42C33B: Vector_softRemove (Vector.c:268)
==3122235==    by 0x42ADB3: Table_removeIndex (Table.c:79)
==3122235==    by 0x42B313: Table_cleanupRow (Table.c:348)
==3122235==    by 0x4233DF: ProcessTable_cleanupEntries (ProcessTable.c:77)
==3122235==    by 0x41B3C7: Machine_scanTables (Machine.c:125)
==3122235==    by 0x4115F7: actionToggleUserlandThreads (Action.c:250)
==3122235==    by 0x41B7E3: MainPanel_eventHandler (MainPanel.c:116)
==3122235==    by 0x4263DF: ScreenManager_run (ScreenManager.c:334)
==3122235==    by 0x4154B7: CommandLine_run (CommandLine.c:407)
==3122235==    by 0x410CF7: main (htop.c:17)
==3122235==  Block was alloc'd at
==3122235==    at 0x48C7BAC: calloc (vg_replace_malloc.c:1675)
==3122235==    by 0x42C747: xCalloc (XUtils.c:57)
==3122235==    by 0x43178F: LinuxProcess_new (LinuxProcess.c:118)
==3122235==    by 0x4234F7: ProcessTable_getProcess (ProcessTable.c:39)
==3122235==    by 0x433AF3: LinuxProcessTable_recurseProcTree (LinuxProcessTable.c:1507)
==3122235==    by 0x433B2F: LinuxProcessTable_recurseProcTree (LinuxProcessTable.c:1514)
==3122235==    by 0x43449B: ProcessTable_goThroughEntries (LinuxProcessTable.c:1834)
==3122235==    by 0x42343F: ProcessTable_iterateEntries (ProcessTable.c:59)
==3122235==    by 0x41B3B3: Machine_scanTables (Machine.c:122)
==3122235==    by 0x41547B: CommandLine_run (CommandLine.c:399)
==3122235==    by 0x410CF7: main (htop.c:17)

[cgzones]

Should be addressed by #1519; thanks for reporting!