From 3ec12efecc8336a17f8732731607afdc293af208 Mon Sep 17 00:00:00 2001 From: Pierre Beyssac Date: Mon, 15 Nov 1999 20:04:53 +0000 Subject: [PATCH] Fix aliasing bug causing in_cksum() to fail on odd packet sizes due to compiler optimization. PR: bin/13292 Suggested by: wollman --- sbin/ping/ping.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/sbin/ping/ping.c b/sbin/ping/ping.c index edbc82a22c2d..f96774da6a40 100644 --- a/sbin/ping/ping.c +++ b/sbin/ping/ping.c @@ -929,7 +929,10 @@ in_cksum(addr, len) register int nleft = len; register u_short *w = addr; register int sum = 0; - u_short answer = 0; + union { + u_int16_t us; + u_int8_t uc[2]; + } answer; /* * Our algorithm is simple, using a 32 bit accumulator (sum), we add @@ -943,15 +946,16 @@ in_cksum(addr, len) /* mop up an odd byte, if necessary */ if (nleft == 1) { - *(u_char *)(&answer) = *(u_char *)w ; - sum += answer; + answer.uc[0] = *(u_char *)w; + answer.uc[1] = 0; + sum += answer.us; } /* add back carry outs from top 16 bits to low 16 bits */ sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ sum += (sum >> 16); /* add carry */ - answer = ~sum; /* truncate to 16 bits */ - return(answer); + answer.us = ~sum; /* truncate to 16 bits */ + return(answer.us); } /*