Null pointer dereference vulnerability in the function d_cresc()

[SegfaultMasters]

Tested environment : 64-bit ubuntu 16.04 LTS

Affected version : 8.14.1-master

Command :
./abcm2ps r -E -g -x -v -O fff -O = -i -k 1 $POC -s 10 -w 1 -m 100 -d 100 -a 0 -f musicfont.fmt -D Bar/ -p -l -I 500 -x -M -N 3 -1 -G -j 0 -b 1 -f -T all -c -B 10

s2 = de->s;
de1 = de->start;		
if (de1) {
s = de1->s;
x = s->x + 3;}

Debug:

GDB :

de1 = de->start;
	 		s = de1->s;
   	 		x = s->x + 3;
   	 //	} else {			/* end without start */
   	 //		if (!first_note) {
   	 //			dd = &deco_def_tb[de->t];
   	 //	 		error(1, s2, "No start of deco !%s!", dd->name);
────────────────────────────────────────────────────────────────────────────────────────────────────────
[#0] Id 1, Name: "abcm2ps", stopped, reason: SIGSEGV
────────────────────────────────────────────────────────────────────────────────────────────────────────
[#0] 0x555555567141 → d_cresc(de=0x5555557eb610)
[#1] 0x5555555698e8 → draw_deco_staff()
[#2] 0x555555572d48 → draw_sym_near()
[#3] 0x555555583dbd → delayed_output(indent=0)
[#4] 0x555555583dbd → output_music()
[#5] 0x555555589501 → generate()
[#6] 0x555555589a78 → gen_ly(eob=0x0)
[#7] 0x55555558f8f8 → do_tune()
[#8] 0x555555561a52 → abc_parse(p=0x5555557f4a20 "", fname=0x5555557f39f0 "POC", ln=0x16b)
[#9] 0x555555579a54 → txt_add_eos(fname=0x5555557f39f0 "POC", linenum=0x16b)

gef➤  p de1
$1 = (struct deco_elt *) 0x0
gef➤  p *de1
Cannot access memory at address 0x0
gef➤  p *de1->s
Cannot access memory at address 0x10

gef➤   i r 
rax            0x1	0x1
rbx            0x5555557eb610	0x5555557eb610
rcx            0x1b	0x1b
rdx            0xc0	0xc0
rsi            0x1	0x1
rdi            0x5555557eb610	0x5555557eb610
rbp            0x5555557be800	0x5555557be800 <deco_def_tb+96>
rsp            0x7fffffffd4c0	0x7fffffffd4c0
r8             0x0	0x0
r9             0x5555557eb610	0x5555557eb610
r10            0x0	0x0
r11            0x5555557e8390	0x5555557e8390
r12            0x0	0x0
r13            0x5555557be7a0	0x5555557be7a0
r14            0x0	0x0
r15            0x5555557c5760	0x5555557c5760
rip            0x555555567141	0x555555567141 <d_cresc+49>
eflags         0x10202	[ IF RF ]
cs             0x33	0x33
ss             0x2b	0x2b
ds             0x0	0x0
es             0x0	0x0
fs             0x0	0x0
gs             0x0	0x0

Valgrind :

Process terminating with default action of signal 11 (SIGSEGV)
Access not within mapped region at address 0x10
 at 0x11B141: d_cresc (deco.c:359)
 by 0x11D8E7: draw_deco_staff (deco.c:1908)
 by 0x126D47: draw_sym_near (draw.c:4216)
 by 0x137DBC: delayed_output (music.c:5085)
 by 0x137DBC: output_music (music.c:5140)
 by 0x13D500: generate (parse.c:1039)
 by 0x13DA77: gen_ly (parse.c:1060)
 by 0x1438F7: do_tune (parse.c:3633)
 by 0x115A51: abc_parse (abcparse.c:177)
 by 0x12DA53: txt_add_eos (front.c:379)
 by 0x12DEE3: frontend (front.c:891)
 by 0x110E2C: treat_file (abcm2ps.c:240)
 by 0x10F9E0: main (abcm2ps.c:1033)
Segmentation fault

Reproducer file - Reproducer