net: add BUG_ON if kernel advertises msg_namelen > sizeof(struct sockaddr_storage)

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=68c6beb373955da0886d8f4f5995b3922ceda4be
Commit:     68c6beb373955da0886d8f4f5995b3922ceda4be
Parent:     f3d3342602f8bcbf37d7c46641cb9bca7618eb1c
Author:     Hannes Frederic Sowa <hannes at stressinduktion.org>
AuthorDate: Thu Nov 21 03:14:34 2013 +0100
Committer:  David S. Miller <davem at davemloft.net>
CommitDate: Wed Nov 20 21:52:30 2013 -0500

    net: add BUG_ON if kernel advertises msg_namelen > sizeof(struct sockaddr_storage)
    
    In that case it is probable that kernel code overwrote part of the
    stack. So we should bail out loudly here.
    
    The BUG_ON may be removed in future if we are sure all protocols are
    conformant.
    
    Suggested-by: Eric Dumazet <eric.dumazet at gmail.com>
    Signed-off-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
    Signed-off-by: David S. Miller <davem at davemloft.net>
---
 net/socket.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/socket.c b/net/socket.c
index fc28556..0b18693 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -221,12 +221,13 @@ static int move_addr_to_user(struct sockaddr_storage *kaddr, int klen,
 	int err;
 	int len;
 
+	BUG_ON(klen > sizeof(struct sockaddr_storage));
 	err = get_user(len, ulen);
 	if (err)
 		return err;
 	if (len > klen)
 		len = klen;
-	if (len < 0 || len > sizeof(struct sockaddr_storage))
+	if (len < 0)
 		return -EINVAL;
 	if (len) {
 		if (audit_sockaddr(klen, kaddr))