path: root/net/netlink
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authorAl Viro <viro@zeniv.linux.org.uk>2014-12-13 04:02:36 (GMT)
committerAl Viro <viro@zeniv.linux.org.uk>2015-02-04 06:34:13 (GMT)
commita8866ff6a5bce7d0ec465a63bc482a85c09b0d39 (patch)
treeba7534a7245d5230860564bb1e936a22a1c97e0c /net/netlink
parent4c72c53be5e3c8cf319a020ea671ab0fc32ec96f (diff)
netlink: make the check for "send from tx_ring" deterministic
As it is, zero msg_iovlen means that the first iovec in the kernel array of iovecs is left uninitialized, so checking if its ->iov_base is NULL is random. Since the real users of that thing are doing sendto(fd, NULL, 0, ...), they are getting msg_iovlen = 1 and msg_iov[0] = {NULL, 0}, which is what this test is trying to catch. As suggested by davem, let's just check that msg_iovlen was 1 and msg_iov[0].iov_base was NULL - _that_ is well-defined and it catches what we want to catch. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'net/netlink')
1 files changed, 5 insertions, 0 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index a36777b..4fd38a6 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2298,7 +2298,12 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
goto out;
+ /* It's a really convoluted way for userland to ask for mmaped
+ * sendmsg(), but that's what we've got...
+ */
if (netlink_tx_is_mmaped(sk) &&
+ msg->msg_iter.type == ITER_IOVEC &&
+ msg->msg_iter.nr_segs == 1 &&
msg->msg_iter.iov->iov_base == NULL) {
err = netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group,

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