Commit 53ea2076 authored Sep 02, 2020 by Magnus Karlsson Committed by Daniel Borkmann Sep 02, 2020

xsk: Fix possible segfault in xsk umem diagnostics

Fix possible segfault in the xsk diagnostics code when dumping
information about the umem. This can happen when a umem has been
created, but the socket has not been bound yet. In this case, the xsk
buffer pool does not exist yet and we cannot dump the information
that was moved from the umem to the buffer pool. Fix this by testing
for the existence of the buffer pool and if not there, do not dump any
of that information.

Fixes: c2d3d6a4 ("xsk: Move queue_id, dev and need_wakeup to buffer pool")
Fixes: 7361f9c3 ("xsk: Move fill and completion rings to buffer pool")
Reported-by: <syzbot+3f04d36b7336f7868066@syzkaller.appspotmail.com>
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1599036743-26454-1-git-send-email-magnus.karlsson@intel.com

parent 858e8b2e

net/xdp/xsk_diag.c

+6 −8

Original line number	Diff line number	Diff line
		@@ -59,22 +59,20 @@ static int xsk_diag_put_umem(const struct xdp_sock xs, struct sk_buff nlskb)
		du.num_pages = umem->npgs;
		du.chunk_size = umem->chunk_size;
		du.headroom = umem->headroom;
		du.ifindex = pool->netdev ? pool->netdev->ifindex : 0;
		du.queue_id = pool->queue_id;
		du.ifindex = (pool && pool->netdev) ? pool->netdev->ifindex : 0;
		du.queue_id = pool ? pool->queue_id : 0;
		du.flags = 0;
		if (umem->zc)
		du.flags \|= XDP_DU_F_ZEROCOPY;
		du.refs = refcount_read(&umem->users);

		err = nla_put(nlskb, XDP_DIAG_UMEM, sizeof(du), &du);

		if (!err && pool->fq)
		if (!err && pool && pool->fq)
		err = xsk_diag_put_ring(pool->fq,
		XDP_DIAG_UMEM_FILL_RING, nlskb);
		if (!err && pool->cq) {
		err = xsk_diag_put_ring(pool->cq, XDP_DIAG_UMEM_COMPLETION_RING,
		nlskb);
		}
		if (!err && pool && pool->cq)
		err = xsk_diag_put_ring(pool->cq,
		XDP_DIAG_UMEM_COMPLETION_RING, nlskb);
		return err;
		}