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[IPV4] ip_fragment: Always compute hash with ipfrag_lock held.

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Otherwise we could compute an inaccurate hash due to the
random seed changing.

Noticed by Zach Brown and patch is based upon some feedback
from Herbert Xu.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2006-04-09 22:43:55 -07:00
parent 19910d1aec
commit 55c0022e53
1 changed files with 10 additions and 5 deletions
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15
net/ipv4/ip_fragment.c
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@ -304,13 +304,17 @@ out:
/* Creation primitives. */
static struct ipq *ip_frag_intern(unsigned int hash, struct ipq *qp_in)
static struct ipq *ip_frag_intern(struct ipq *qp_in)
{
struct ipq *qp;
#ifdef CONFIG_SMP
struct hlist_node *n;
#endif
unsigned int hash;
write_lock(&ipfrag_lock);
hash = ipqhashfn(qp_in->id, qp_in->saddr, qp_in->daddr,
qp_in->protocol);
#ifdef CONFIG_SMP
/* With SMP race we have to recheck hash table, because
* such entry could be created on other cpu, while we
@ -345,7 +349,7 @@ static struct ipq *ip_frag_intern(unsigned int hash, struct ipq *qp_in)
}
/* Add an entry to the 'ipq' queue for a newly received IP datagram. */
static struct ipq *ip_frag_create(unsigned hash, struct iphdr *iph, u32 user)
static struct ipq *ip_frag_create(struct iphdr *iph, u32 user)
{
struct ipq *qp;
@ -371,7 +375,7 @@ static struct ipq *ip_frag_create(unsigned hash, struct iphdr *iph, u32 user)
spin_lock_init(&qp->lock);
atomic_set(&qp->refcnt, 1);
return ip_frag_intern(hash, qp);
return ip_frag_intern(qp);
out_nomem:
LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n");
@ -387,11 +391,12 @@ static inline struct ipq *ip_find(struct iphdr *iph, u32 user)
__u32 saddr = iph->saddr;
__u32 daddr = iph->daddr;
__u8 protocol = iph->protocol;
unsigned int hash = ipqhashfn(id, saddr, daddr, protocol);
unsigned int hash;
struct ipq *qp;
struct hlist_node *n;
read_lock(&ipfrag_lock);
hash = ipqhashfn(id, saddr, daddr, protocol);
hlist_for_each_entry(qp, n, &ipq_hash[hash], list) {
if(qp->id == id &&
qp->saddr == saddr &&
@ -405,7 +410,7 @@ static inline struct ipq *ip_find(struct iphdr *iph, u32 user)
}
read_unlock(&ipfrag_lock);
return ip_frag_create(hash, iph, user);
return ip_frag_create(iph, user);
}
/* Is the fragment too far ahead to be part of ipq? */