Commit 70612567 authored Feb 25, 2020 by Vasily Averin Committed by Greg Kroah-Hartman Mar 18, 2020

netfilter: x_tables: xt_mttg_seq_next should increase position index

commit ee84f19cbbe9cf7cba2958acb03163fed3ecbb0f upstream.

If .next function does not change position index,
following .show function will repeat output related
to current position index.

Without patch:
 # dd if=/proc/net/ip_tables_matches  # original file output
 conntrack
 conntrack
 conntrack
 recent
 recent
 icmp
 udplite
 udp
 tcp
 0+1 records in
 0+1 records out
 65 bytes copied, 5.4074e-05 s, 1.2 MB/s

 # dd if=/proc/net/ip_tables_matches bs=62 skip=1
 dd: /proc/net/ip_tables_matches: cannot skip to specified offset
 cp   <<< end of  last line
 tcp  <<< and then unexpected whole last line once again
 0+1 records in
 0+1 records out
 7 bytes copied, 0.000102447 s, 68.3 kB/s

Cc: stable@vger.kernel.org
Fixes: 1f4aace6 ("fs/seq_file.c: simplify seq_file iteration code ...")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206283


Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent bfacd280

net/netfilter/x_tables.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1551,6 +1551,9 @@ static void xt_mttg_seq_next(struct seq_file seq, void v, loff_t ppos,
		uint8_t nfproto = (unsigned long)PDE_DATA(file_inode(seq->file));
		struct nf_mttg_trav *trav = seq->private;

		if (ppos != NULL)
		++(*ppos);

		switch (trav->class) {
		case MTTG_TRAV_INIT:
		trav->class = MTTG_TRAV_NFP_UNSPEC;
		@@ -1576,9 +1579,6 @@ static void xt_mttg_seq_next(struct seq_file seq, void v, loff_t ppos,
		default:
		return NULL;
		}

		if (ppos != NULL)
		++*ppos;
		return trav;
		}