Comment 22 for bug 1974214

--- exim4-4.96~RC0.orig/src/arc.c
+++ exim4-4.96~RC0/src/arc.c
@@ -90,7 +90,7 @@ typedef struct arc_ctx {

 static time_t now;
 static time_t expire;
-static hdr_rlist * headers_rlist;
+static hdr_rlist * headers_rlist = NULL;
 static arc_ctx arc_sign_ctx = { NULL };
 static arc_ctx arc_verify_ctx = { NULL };

Core was generated by `/usr/sbin/exim4 -q'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00005599b240c993 in arc_sign (signspec=<optimized out>, sigheaders=0x5599b2fea580, errstr=errstr@entry=0x7ffeafba7af0) at ./b-exim4-daemon-custom/build-Linux-x86_64/arc.c:1663
1663 ./b-exim4-daemon-custom/build-Linux-x86_64/arc.c: No such file or directory.
(gdb) set pagination off
(gdb) bt full
#0 0x00005599b240c993 in arc_sign (signspec=<optimized out>, sigheaders=0x5599b2fea580, errstr=errstr@entry=0x7ffeafba7af0) at ./b-exim4-daemon-custom/build-Linux-x86_64/arc.c:1663
        rp = 0x672e6c69616d3d48
        identity = 0x5599b2fea8a8 "****.com"
        selector = 0x5599b2fea8c8 "arc-20220506"
        privkey = 0x5599b2bdc2f8 "-----BEGIN PRIVATE KEY-----\n"...
        opts = 0x5599b2fea92a ""
        s = <optimized out>
        options = <optimized out>
        sep = 58
        headers = <optimized out>
        rheaders = 0x5599b2fea950
        ar = {data = <optimized out>, len = <optimized out>}
        instance = <optimized out>
        g = 0x0
        b = <optimized out>
        __FUNCTION__ = "arc_sign"
        ret_sigheaders = <optimized out>

(gdb) p *rp
Cannot access memory at address 0x672e6c69616d3d48
(gdb) p headers_rlist
$1 = (hdr_rlist *) 0x5599b3177d78