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author | Pierre Beyssac <pb@FreeBSD.org> | 1999-11-15 20:04:53 +0000 |
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committer | Pierre Beyssac <pb@FreeBSD.org> | 1999-11-15 20:04:53 +0000 |
commit | 3ec12efecc8336a17f8732731607afdc293af208 (patch) | |
tree | fa6369b19a12b8c2b2309ae0d02395e84bb77599 | |
parent | 309c48c65ba8b554b24e6d48256b322bb4d7b19c (diff) | |
download | src-3ec12efecc8336a17f8732731607afdc293af208.tar.gz src-3ec12efecc8336a17f8732731607afdc293af208.zip |
Fix aliasing bug causing in_cksum() to fail on odd packet sizes
due to compiler optimization.
PR: bin/13292
Suggested by: wollman
Notes
Notes:
svn path=/head/; revision=53191
-rw-r--r-- | sbin/ping/ping.c | 14 |
1 files 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); } /* |