bpf: Fix bpf_msg_pull_data() (9db39f4d) · Commits · 戴 / test

Helper bpf_msg_pull_data() mistakenly reuses variable 'offset' while linearizing multiple scatterlist elements. Variable 'offset' is used to find first starting scatterlist element i.e. msg->data = sg_virt(&sg[first_sg]) + start - offset" Use different variable name while linearizing multiple scatterlist elements so that value contained in variable 'offset' won't get overwritten. Fixes: ("bpf: sk_msg program helper bpf_sk_msg_pull_data") Signed-off-by:

Tushar Dave <tushar.n.dave@oracle.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net>

net/core/filter.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -2292,7 +2292,7 @@ static const struct bpf_func_proto bpf_msg_cork_bytes_proto = {
		BPF_CALL_4(bpf_msg_pull_data,
		struct sk_msg_buff *, msg, u32, start, u32, end, u64, flags)
		{
		unsigned int len = 0, offset = 0, copy = 0;
		unsigned int len = 0, offset = 0, copy = 0, poffset = 0;
		int bytes = end - start, bytes_sg_total;
		struct scatterlist *sg = msg->sg_data;
		int first_sg, last_sg, i, shift;
		@@ -2348,16 +2348,15 @@ BPF_CALL_4(bpf_msg_pull_data,
		if (unlikely(!page))
		return -ENOMEM;
		p = page_address(page);
		offset = 0;

		i = first_sg;
		do {
		from = sg_virt(&sg[i]);
		len = sg[i].length;
		to = p + offset;
		to = p + poffset;

		memcpy(to, from, len);
		offset += len;
		poffset += len;
		sg[i].length = 0;
		put_page(sg_page(&sg[i]));

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