Date: Wed, 27 Feb 2002 13:04:59 -0800 From: Rob Braun <bbraun@FreeBSD.ORG> To: freebsd-net@FreeBSD.ORG Subject: proposed changes to getnameinfo() implementation Message-ID: <200202272105.g1RL50J21344@lh.synack.net>
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getnameinfo() takes a struct sockaddr pointer, and a length
parameter for the amount of memory pointed to by the struct
sockaddr pointer.
The current FreeBSD implementation of getnameinfo() does
2 problematic checks against the length parameter. First,
it makes sure the length parameter is equal to the length
specified in the passed in sockaddr structure. This is
problematic because the length parameter refers to the
amount of memory pointed to by the first parameter, and
the struct sockaddr sa_len field is used to specify the
size of the sockaddr structure, since there are different
types of sockaddr structures with different lengths.
I propose to change this exact match comparison to ensure
that the length passed in is at least what the sa_len
field is. This will allow a larger structure to be passed
in than the size of the sockaddr structure for the desired
protocol.
The second comparison is similar to the first. The passed
in length field is compared to the size of the sockaddr
structure for the address family you're using. Again, I
propose to make sure that the passed in length is at least
as large as the known structure length.
With these changes, it still ensure that enough memory is
available to proceed, but it also allows more memory than
is needed.
Rob
diff -u -d -b -w -u -d -r1.7 getnameinfo.c
--- getnameinfo.c 2001/02/15 10:35:54 1.7
+++ getnameinfo.c 2002/02/27 20:48:14
@@ -119,7 +119,7 @@
if (sa == NULL)
return ENI_NOSOCKET;
- if (sa->sa_len != salen)
+ if (sa->sa_len > salen)
return ENI_SALEN;
family = sa->sa_family;
@@ -131,7 +131,7 @@
return ENI_FAMILY;
found:
- if (salen != afd->a_socklen)
+ if (salen < afd->a_socklen)
return ENI_SALEN;
/* network byte order */
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