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ctdb-common: Avoid aliasing errors during code optimization

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When compiling with GCC 10.x and -O3 optimization, the IP checksum
calculation code generates wrong checksum.  The function uint16_checksum
gets inlined during optimization and ip4pkt->tcp data gets wrongly
aliased.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14537

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>

Autobuild-User(master): Martin Schwenke <martins@samba.org>
Autobuild-Date(master): Wed Oct 21 05:52:28 UTC 2020 on sn-devel-184
This commit is contained in:
Amitay Isaacs 2020-07-27 12:51:41 +10:00 committed by Martin Schwenke
parent 9dfeb81d08
commit 6aa396b0cd
1 changed files with 17 additions and 14 deletions
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31
ctdb/common/system_socket.c
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@ -67,16 +67,19 @@
/*
uint16 checksum for n bytes
*/
static uint32_t uint16_checksum(uint16_t *data, size_t n)
static uint32_t uint16_checksum(uint8_t *data, size_t n)
{
uint32_t sum=0;
uint16_t value;
while (n>=2) {
sum += (uint32_t)ntohs(*data);
data++;
memcpy(&value, data, 2);
sum += (uint32_t)ntohs(value);
data += 2;
n -= 2;
}
if (n == 1) {
sum += (uint32_t)ntohs(*(uint8_t *)data);
sum += (uint32_t)ntohs(*data);
}
return sum;
}
@ -117,13 +120,13 @@ bool ctdb_sys_have_ip(ctdb_sock_addr *_addr)
/*
* simple TCP checksum - assumes data is multiple of 2 bytes long
*/
static uint16_t ip_checksum(uint16_t *data, size_t n, struct ip *ip)
static uint16_t ip_checksum(uint8_t *data, size_t n, struct ip *ip)
{
uint32_t sum = uint16_checksum(data, n);
uint16_t sum2;
sum += uint16_checksum((uint16_t *)&ip->ip_src, sizeof(ip->ip_src));
sum += uint16_checksum((uint16_t *)&ip->ip_dst, sizeof(ip->ip_dst));
sum += uint16_checksum((uint8_t *)&ip->ip_src, sizeof(ip->ip_src));
sum += uint16_checksum((uint8_t *)&ip->ip_dst, sizeof(ip->ip_dst));
sum += ip->ip_p + n;
sum = (sum & 0xFFFF) + (sum >> 16);
sum = (sum & 0xFFFF) + (sum >> 16);
@ -135,22 +138,22 @@ static uint16_t ip_checksum(uint16_t *data, size_t n, struct ip *ip)
return sum2;
}
static uint16_t ip6_checksum(uint16_t *data, size_t n, struct ip6_hdr *ip6)
static uint16_t ip6_checksum(uint8_t *data, size_t n, struct ip6_hdr *ip6)
{
uint16_t phdr[3];
uint32_t sum = 0;
uint16_t sum2;
uint32_t len;
sum += uint16_checksum((uint16_t *)(void *)&ip6->ip6_src, 16);
sum += uint16_checksum((uint16_t *)(void *)&ip6->ip6_dst, 16);
sum += uint16_checksum((uint8_t *)&ip6->ip6_src, 16);
sum += uint16_checksum((uint8_t *)&ip6->ip6_dst, 16);
len = htonl(n);
phdr[0] = len & UINT16_MAX;
phdr[1] = (len >> 16) & UINT16_MAX;
/* ip6_nxt is only 8 bits, so fits comfortably into a uint16_t */
phdr[2] = htons(ip6->ip6_nxt);
sum += uint16_checksum(phdr, sizeof(phdr));
sum += uint16_checksum((uint8_t *)phdr, sizeof(phdr));
sum += uint16_checksum(data, n);
@ -316,7 +319,7 @@ static int ip6_na_build(uint8_t *buffer,
sizeof(struct nd_opt_hdr));
memcpy(ea, hwaddr, ETH_ALEN);
nd_na->nd_na_cksum = ip6_checksum((uint16_t *)nd_na,
nd_na->nd_na_cksum = ip6_checksum((uint8_t *)nd_na,
ntohs(ip6->ip6_plen),
ip6);
@ -556,7 +559,7 @@ static int tcp4_build(uint8_t *buf,
ip4pkt->tcp.th_off = sizeof(ip4pkt->tcp)/sizeof(uint32_t);
/* this makes it easier to spot in a sniffer */
ip4pkt->tcp.th_win = htons(1234);
ip4pkt->tcp.th_sum = ip_checksum((uint16_t *)&ip4pkt->tcp,
ip4pkt->tcp.th_sum = ip_checksum((uint8_t *)&ip4pkt->tcp,
sizeof(ip4pkt->tcp),
&ip4pkt->ip);
@ -609,7 +612,7 @@ static int tcp6_build(uint8_t *buf,
ip6pkt->tcp.th_off = sizeof(ip6pkt->tcp)/sizeof(uint32_t);
/* this makes it easier to spot in a sniffer */
ip6pkt->tcp.th_win = htons(1234);
ip6pkt->tcp.th_sum = ip6_checksum((uint16_t *)&ip6pkt->tcp,
ip6pkt->tcp.th_sum = ip6_checksum((uint8_t *)&ip6pkt->tcp,
sizeof(ip6pkt->tcp),
&ip6pkt->ip6);