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slirp: fix unaligned access in bootp code

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Slirp code tries to be smart an avoid data copy by using pointer to
the data. This solution leads to unaligned access, in this case
preq_addr, which is a 32-bit long structure. There is no real point
of avoiding data copy in a such case, as the value itself is smaller
or the same size as a pointer.

The patch replaces pointers to the preq_addr structure by the strcture
itself, and use the address 0.0.0.0 if no address has been requested
(this is not a valid address in such a request). It compares it with
htonl(0L) for correctness reasons, in case a code checker look for such
mistakes. It also uses memcpy() for copying the data, which takes care
of alignement issues.

This fixes an unaligned access on IA64 host while requesting a DHCP
address.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Aurelien Jarno 2011-01-06 22:43:13 +01:00
parent 102c29769f
commit 8aaf42ed0f
1 changed files with 17 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
slirp/bootp.c
View File

@ -92,13 +92,13 @@ static BOOTPClient *find_addr(Slirp *slirp, struct in_addr *paddr,
}
static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
const struct in_addr **preq_addr)
struct in_addr *preq_addr)
{
const uint8_t *p, *p_end;
int len, tag;
*pmsg_type = 0;
*preq_addr = NULL;
preq_addr->s_addr = htonl(0L);
p = bp->bp_vend;
p_end = p + DHCP_OPT_LEN;
@ -124,8 +124,9 @@ static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
*pmsg_type = p[0];
break;
case RFC2132_REQ_ADDR:
if (len >= 4)
*preq_addr = (struct in_addr *)p;
if (len >= 4) {
memcpy(&(preq_addr->s_addr), p, 4);
}
break;
default:
break;
@ -133,8 +134,9 @@ static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
p += len;
}
}
if (*pmsg_type == DHCPREQUEST && !*preq_addr && bp->bp_ciaddr.s_addr) {
*preq_addr = &bp->bp_ciaddr;
if (*pmsg_type == DHCPREQUEST && preq_addr->s_addr == htonl(0L) &&
bp->bp_ciaddr.s_addr) {
memcpy(&(preq_addr->s_addr), &bp->bp_ciaddr, 4);
}
}
@ -144,15 +146,15 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
struct mbuf *m;
struct bootp_t *rbp;
struct sockaddr_in saddr, daddr;
const struct in_addr *preq_addr;
struct in_addr preq_addr;
int dhcp_msg_type, val;
uint8_t *q;
/* extract exact DHCP msg type */
dhcp_decode(bp, &dhcp_msg_type, &preq_addr);
DPRINTF("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type);
if (preq_addr)
DPRINTF(" req_addr=%08x\n", ntohl(preq_addr->s_addr));
if (preq_addr.s_addr != htonl(0L))
DPRINTF(" req_addr=%08x\n", ntohl(preq_addr.s_addr));
else
DPRINTF("\n");
@ -175,10 +177,10 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
memset(rbp, 0, sizeof(struct bootp_t));
if (dhcp_msg_type == DHCPDISCOVER) {
if (preq_addr) {
bc = request_addr(slirp, preq_addr, slirp->client_ethaddr);
if (preq_addr.s_addr != htonl(0L)) {
bc = request_addr(slirp, &preq_addr, slirp->client_ethaddr);
if (bc) {
daddr.sin_addr = *preq_addr;
daddr.sin_addr = preq_addr;
}
}
if (!bc) {
@ -190,10 +192,10 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
}
}
memcpy(bc->macaddr, slirp->client_ethaddr, 6);
} else if (preq_addr) {
bc = request_addr(slirp, preq_addr, slirp->client_ethaddr);
} else if (preq_addr.s_addr != htonl(0L)) {
bc = request_addr(slirp, &preq_addr, slirp->client_ethaddr);
if (bc) {
daddr.sin_addr = *preq_addr;
daddr.sin_addr = preq_addr;
memcpy(bc->macaddr, slirp->client_ethaddr, 6);
} else {
daddr.sin_addr.s_addr = 0;