#2755 SEGV on CANVAS_text()

[liuchenyifan]

version: gnuplot 6.1 last modified 2025-01-11
system: ubuntu 20.04

use this command to reproduce: gnutplot poc
message from ASAN:
==1280300==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000010 (pc 0x55e8a3d3f340 bp 0x55e8a3f87968 sp 0x7ffcf18b2ca0 T0)
==1280300==The signal is caused by a READ memory access.
==1280300==Hint: address points to the zero page.
#0 0x55e8a3d3f33f in CANVAS_text ../term/canvas.trm:660
#1 0x55e8a3d60722 in term_end_plot /home/fizz/target_program/tmp/gnuplot-main/src/term.c:557
#2 0x55e8a3d60722 in term_end_plot /home/fizz/target_program/tmp/gnuplot-main/src/term.c:545
#3 0x55e8a39ab494 in do_plot /home/fizz/target_program/tmp/gnuplot-main/src/graphics.c:1243
#4 0x55e8a3824db4 in refresh_request /home/fizz/target_program/tmp/gnuplot-main/src/command.c:2510
#5 0x55e8a3824db4 in refresh_request /home/fizz/target_program/tmp/gnuplot-main/src/command.c:2460
#6 0x55e8a38179b1 in command /home/fizz/target_program/tmp/gnuplot-main/src/command.c:855
#7 0x55e8a38179b1 in step_through_line /home/fizz/target_program/tmp/gnuplot-main/src/command.c:549
#8 0x55e8a3a273af in load_file /home/fizz/target_program/tmp/gnuplot-main/src/misc.c:393
#9 0x55e8a37ae548 in main /home/fizz/target_program/tmp/gnuplot-main/src/plot.c:669
#10 0x7f496846c082 in __libc_start_main ../csu/libc-start.c:308
#11 0x55e8a37afb4d in _start (/home/fizz/target_program/gnuplot-main/output/gnuplot_asan+0xd3b4d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV ../term/canvas.trm:660 in CANVAS_text
==1280300==ABORTING

[Ethan Merritt]

Fixed in 6.1
queued for 6.0