netdev - [PATCH RFC v1 09/15] xdp: clear grow memory in bpf_xdp_adjust

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Message-ID: <158446619342.702578.1522482431365026926.stgit@firesoul>
Date:   Tue, 17 Mar 2020 18:29:53 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     sameehj@...zon.com
Cc:     Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, zorik@...zon.com, akiyano@...zon.com,
        gtzalik@...zon.com,
        Toke Høiland-Jørgensen <toke@...e.dk>,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        David Ahern <dsahern@...il.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Lorenzo Bianconi <lorenzo@...nel.org>
Subject: [PATCH RFC v1 09/15] xdp: clear grow memory in bpf_xdp_adjust_tail()

To reviewers: Need some opinions if this is needed?

(TODO: Squash patch)
---
 net/core/filter.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 0ceddee0c678..669f29992177 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3432,6 +3432,12 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)
 	if (unlikely(data_end < xdp->data + ETH_HLEN))
 		return -EINVAL;
 
+	// XXX: To reviewers: How paranoid are we? Do we really need to
+	/* clear memory area on grow, as in-theory can contain uninit kmem */
+	if (offset > 0) {
+		memset(xdp->data_end, 0, offset);
+	}
+
 	xdp->data_end = data_end;
 
 	return 0;