segfault rendering man7/man.html #719
Description
Diagnosing this was made more difficult by libthread/daemonize.c declaring a null signal handler for SIGSEGV, the only indication was from Linux kernel messages at the end of compilation.
Analysis from core of troff2html:
#0 0x000055f15de7583b in iputs (b=0x55f15de853c0 <bout>,
s=0x31 <error: Cannot access memory at address 0x31>) at troff2html.c:341
341 if(s[0]=='<' && s[1]=='+'){
(gdb) up
#1 0x000055f15de75aaf in setattr (a=94495150899200) at troff2html.c:391
391 iputs(&bout, onattr[j]);
(gdb) print j
$1 = 26
(gdb) l
386 for(i=0; i<nelem(attrorder); i++){
387 j = attrorder[i];
388 if(on&(1<<j)){
389 if(j == Anchor)
390 onattr[j] = anchors[nanchors++];
391 iputs(&bout, onattr[j]);
392 nest[nnest++] = j;
393 }
394 }
395 attr = a;
(gdb) print Anchor+0
$2 = 26
(gdb) print nanchors
$3 = 4
(gdb) print anchors[3]
$4 = 0x31 <error: Cannot access memory at address 0x31>
I couldn't figure out what a correction would be; the values of the nonexistent anchors never made it into the final html file. But as nanchors is a global, and the anchors array is filled elsewhere, increasing nanchors here looks suspicious.