bpf: sockmap: initialize sg table entries properly (6ef6d84c) · Commits · 戴 / test

When CONFIG_DEBUG_SG is set, sg->sg_magic is initialized in sg_init_table() and it is verified in sg api while navigating. We hit BUG_ON when magic check is failed. In functions sg_tcp_sendpage and sg_tcp_sendmsg, the struct containing the scatterlist is already zeroed out. So to avoid extra memset, we use sg_init_marker() to initialize sg_magic. Fixed following things: - In bpf_tcp_sendpage: initialize sg using sg_init_marker - In bpf_tcp_sendmsg: Replace sg_init_table with sg_init_marker - In bpf_tcp_push: Replace memset with sg_init_table where consumed sg entry needs to be re-initialized. Signed-off-by:

Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp> Acked-by:

John Fastabend <john.fastabend@gmail.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net>

kernel/bpf/sockmap.c

+8 −5

Original line number	Diff line number	Diff line
		@@ -341,7 +341,7 @@ retry:
		md->sg_start++;
		if (md->sg_start == MAX_SKB_FRAGS)
		md->sg_start = 0;
		memset(sg, 0, sizeof(*sg));
		sg_init_table(sg, 1);

		if (md->sg_start == md->sg_end)
		break;
		@@ -843,7 +843,7 @@ static int bpf_tcp_sendmsg(struct sock sk, struct msghdr msg, size_t size)
		}

		sg = md.sg_data;
		sg_init_table(sg, MAX_SKB_FRAGS);
		sg_init_marker(sg, MAX_SKB_FRAGS);
		rcu_read_unlock();

		lock_sock(sk);
		@@ -950,10 +950,14 @@ static int bpf_tcp_sendpage(struct sock sk, struct page page,

		lock_sock(sk);

		if (psock->cork_bytes)
		if (psock->cork_bytes) {
		m = psock->cork;
		else
		sg = &m->sg_data[m->sg_end];
		} else {
		m = &md;
		sg = m->sg_data;
		sg_init_marker(sg, MAX_SKB_FRAGS);
		}

		/* Catch case where ring is full and sendpage is stalled. */
		if (unlikely(m->sg_end == m->sg_start &&
		@@ -961,7 +965,6 @@ static int bpf_tcp_sendpage(struct sock sk, struct page page,
		goto out_err;

		psock->sg_size += size;
		sg = &m->sg_data[m->sg_end];
		sg_set_page(sg, page, size, offset);
		get_page(page);
		m->sg_copy[m->sg_end] = true;

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