Re: [PATCH] app/dumpcap:fix coredump problem because pcap_dump 3th argument is null

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri,  1 Mar 2024 18:41:29 +0800
Tianli Lai <laitianli@tom.com> wrote:

> if rte_pktmbuf_read() return NULL, pcap_dump() would coredump.
> 
> Signed-off-by: Tianli Lai <laitianli@tom.com>

To safely handle jumbo packets, the code here should increase
the size of temp_data, then the RTE_MIN() is not needed either.

See drivers/net/pcap/pcap_ethdev.c

	for (i = 0; i < nb_pkts; i++) {
		mbuf = bufs[i];
		len = caplen = rte_pktmbuf_pkt_len(mbuf);
		if (unlikely(!rte_pktmbuf_is_contiguous(mbuf) &&
				len > sizeof(temp_data))) {
			caplen = sizeof(temp_data);
		}

		calculate_timestamp(&header.ts);
		header.len = len;
		header.caplen = caplen;
		/* rte_pktmbuf_read() returns a pointer to the data directly
		 * in the mbuf (when the mbuf is contiguous) or, otherwise,
		 * a pointer to temp_data after copying into it.
		 */
		pcap_dump((u_char *)dumper, &header,
			rte_pktmbuf_read(mbuf, 0, caplen, temp_data));