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net/garp: avoid infinite loop if attribute already exists 

An infinite loop occurred if garp_attr_create was called with the values
of an existing attribute. This might happen if a previous leave request
for the attribute has not yet been followed by a PDU transmission (or,
if the application previously issued a join request for the attribute
and is now issuing another one, without having issued a leave request).

If garp_attr_create finds an existing attribute having the same values,
return the address to it. Its state will then get updated (i.e., if it
was in a leaving state, it will move into a non-leaving state and not
get deleted during the next PDU transmission).

To accomplish this fix, collapse garp_attr_insert into garp_attr_create
(which is its only caller).

Thanks to Jorge Boncompte [DTI2] <jorge@dti2.net> for contributing to
this fix.

Signed-off-by: David Ward <david.ward@ll.mit.edu>
Acked-by: Jorge Boncompte [DTI2] <jorge@dti2.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Ward 2012-03-27 09:01:52 +00:00 committed by David S. Miller
parent 54f5ffbf30
commit 67378563df
1 changed files with 10 additions and 12 deletions
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22
net/802/garp.c
View File

@ -167,7 +167,8 @@ static struct garp_attr *garp_attr_lookup(const struct garp_applicant *app,
return NULL;
}
static void garp_attr_insert(struct garp_applicant *app, struct garp_attr *new)
static struct garp_attr *garp_attr_create(struct garp_applicant *app,
const void *data, u8 len, u8 type)
{
struct rb_node *parent = NULL, **p = &app->gid.rb_node;
struct garp_attr *attr;
@ -176,21 +177,16 @@ static void garp_attr_insert(struct garp_applicant *app, struct garp_attr *new)
while (*p) {
parent = *p;
attr = rb_entry(parent, struct garp_attr, node);
d = garp_attr_cmp(attr, new->data, new->dlen, new->type);
d = garp_attr_cmp(attr, data, len, type);
if (d < 0)
p = &parent->rb_left;
else if (d > 0)
p = &parent->rb_right;
else {
/* The attribute already exists; re-use it. */
return attr;
}
}
rb_link_node(&new->node, parent, p);
rb_insert_color(&new->node, &app->gid);
}
static struct garp_attr *garp_attr_create(struct garp_applicant *app,
const void *data, u8 len, u8 type)
{
struct garp_attr *attr;
attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
if (!attr)
return attr;
@ -198,7 +194,9 @@ static struct garp_attr *garp_attr_create(struct garp_applicant *app,
attr->type = type;
attr->dlen = len;
memcpy(attr->data, data, len);
garp_attr_insert(app, attr);
rb_link_node(&attr->node, parent, p);
rb_insert_color(&attr->node, &app->gid);
return attr;
}