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Commit 67378563 authored by David Ward's avatar David Ward Committed by David S. Miller
Browse files

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: default avatarDavid Ward <david.ward@ll.mit.edu>
Acked-by: default avatarJorge Boncompte [DTI2] <jorge@dti2.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 54f5ffbf

net/802/garp.c

+10 −12
Original line number Diff line number Diff line
@@ -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;

}