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netlink: allow empty nested attributes 

validate_nla() currently doesn't allow empty nested attributes. This
makes userspace code unnecessarily complicated when starting and ending
the nested attribute is done by generic upper level code and the inner
attributes are dumped by a module.

Add a special case to accept empty nested attributes. When the nested
attribute is non empty, the same checks as before are performed.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy 2008-11-28 03:05:19 -08:00 committed by David S. Miller
parent ed77a89c30
commit ea5693ccc5
1 changed files with 6 additions and 0 deletions
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6
net/netlink/attr.c
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@ -83,6 +83,12 @@ static int validate_nla(struct nlattr *nla, int maxtype,
if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
return -ERANGE;
break;
case NLA_NESTED:
/* a nested attributes is allowed to be empty; if its not,
* it must have a size of at least NLA_HDRLEN.
*/
if (attrlen == 0)
break;
default:
if (pt->len)
minlen = pt->len;