http://bugs.gentoo.org/104311

From the strncpy(3) manpage:
The strings may not overlap, and the destination string dest must be large 
enough to receive the copy.

ftp.c:1812:Bounds error: in strncpy with 0x4 for 63 and 0x4 for 1, source and destination objects overlap.
ftp.c:1812:  Pointer value: 0x4
ftp.c:1812:  Object `*proxstruct.3':
ftp.c:1812:    Address in memory:    0x0 .. 0x7
ftp.c:1812:    Size:                 8408 bytes
ftp.c:1812:    Element size:         1 bytes
ftp.c:1812:    Number of elements:   8408
ftp.c:1812:    Storage class:        static
Aborted

The bug is hit when ftp.c's pswitch() is called multiple times:

static struct comvars { char name[]; } proxstruct, tmpstruct;
struct comvars *ip, *op;
...
if (flag) {
	ip = &tmpstruct;
	op = &proxstruct;
} else {
	ip = &proxstruct;
	op = &tmpstruct;
}
...
if (hostname)
	strncpy(ip->name, hostname, sizeof(ip->name) - 1);
...
hostname = op->name;

so if the code path is:
	hostname = NULL
	pswitch(0)
	hostname = op->name (tmpstruct.name)
	pswitch(1)
	strncpy(ip->name (tmpstruct.name), hostname, ...)
bad things happen

--- ftp/ftp.c
+++ ftp/ftp.c
@@ -1808,7 +1808,7 @@
 	}
 	ip->connect = connected;
 	connected = op->connect;
-	if (hostname) {
+	if (hostname && ip->name != hostname) {
 		(void) strncpy(ip->name, hostname, sizeof(ip->name) - 1);
 		ip->name[sizeof(ip->name) - 1] = '\0';
 	}