diff options
Diffstat (limited to 'net/ipx/af_ipx.c')
| -rw-r--r-- | net/ipx/af_ipx.c | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/net/ipx/af_ipx.c b/net/ipx/af_ipx.c index c272a38af325..76c661566dfd 100644 --- a/net/ipx/af_ipx.c +++ b/net/ipx/af_ipx.c @@ -1234,27 +1234,27 @@ static int ipxitf_ioctl(unsigned int cmd, void __user *arg) /* Note: We assume ipx_tctrl==0 and htons(length)==ipx_pktsize */ /* This functions should *not* mess with packet contents */ -__u16 ipx_cksum(struct ipxhdr *packet, int length) +__be16 ipx_cksum(struct ipxhdr *packet, int length) { /* * NOTE: sum is a net byte order quantity, which optimizes the * loop. This only works on big and little endian machines. (I * don't know of a machine that isn't.) */ - /* start at ipx_dest - We skip the checksum field and start with - * ipx_type before the loop, not considering ipx_tctrl in the calc */ - __u16 *p = (__u16 *)&packet->ipx_dest; - __u32 i = (length >> 1) - 1; /* Number of complete words */ - __u32 sum = packet->ipx_type << sizeof(packet->ipx_tctrl); - - /* Loop through all complete words except the checksum field, - * ipx_type (accounted above) and ipx_tctrl (not used in the cksum) */ - while (--i) + /* handle the first 3 words separately; checksum should be skipped + * and ipx_tctrl masked out */ + __u16 *p = (__u16 *)packet; + __u32 sum = p[1] + (p[2] & (__force u16)htons(0x00ff)); + __u32 i = (length >> 1) - 3; /* Number of remaining complete words */ + + /* Loop through them */ + p += 3; + while (i--) sum += *p++; /* Add on the last part word if it exists */ if (packet->ipx_pktsize & htons(1)) - sum += ntohs(0xff00) & *p; + sum += (__force u16)htons(0xff00) & *p; /* Do final fixup */ sum = (sum & 0xffff) + (sum >> 16); @@ -1263,7 +1263,14 @@ __u16 ipx_cksum(struct ipxhdr *packet, int length) if (sum >= 0x10000) sum++; - return ~sum; + /* + * Leave 0 alone; we don't want 0xffff here. Note that we can't get + * here with 0x10000, so this check is the same as ((__u16)sum) + */ + if (sum) + sum = ~sum; + + return (__force __be16)sum; } const char *ipx_frame_name(__be16 frame) |