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net: fix iteration for sctp transport seq_files 

commit af8085f3a4712c57d0dd415ad543bac85780375c upstream.

The sctp transport seq_file iterators take a reference to the transport
in the ->start and ->next functions and releases the reference in the
->show function.  The preferred handling for such resources is to
release them in the subsequent ->next or ->stop function call.

Since Commit 1f4aace60b ("fs/seq_file.c: simplify seq_file iteration
code and interface") there is no guarantee that ->show will be called
after ->next, so this function can now leak references.

So move the sctp_transport_put() call to ->next and ->stop.

Fixes: 1f4aace60b ("fs/seq_file.c: simplify seq_file iteration code and interface")
Reported-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
NeilBrown 2021-02-05 11:36:30 +11:00 committed by Greg Kroah-Hartman
parent 2085d88663
commit 611d93fbea
1 changed files with 12 additions and 4 deletions
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16
net/sctp/proc.c
View File

@ -215,6 +215,12 @@ static void sctp_transport_seq_stop(struct seq_file *seq, void *v)
{
struct sctp_ht_iter *iter = seq->private;
if (v && v != SEQ_START_TOKEN) {
struct sctp_transport *transport = v;
sctp_transport_put(transport);
}
sctp_transport_walk_stop(&iter->hti);
}
@ -222,6 +228,12 @@ static void *sctp_transport_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct sctp_ht_iter *iter = seq->private;
if (v && v != SEQ_START_TOKEN) {
struct sctp_transport *transport = v;
sctp_transport_put(transport);
}
++*pos;
return sctp_transport_get_next(seq_file_net(seq), &iter->hti);
@ -277,8 +289,6 @@ static int sctp_assocs_seq_show(struct seq_file *seq, void *v)
sk->sk_rcvbuf);
seq_printf(seq, "\n");
sctp_transport_put(transport);
return 0;
}
@ -354,8 +364,6 @@ static int sctp_remaddr_seq_show(struct seq_file *seq, void *v)
seq_printf(seq, "\n");
}
sctp_transport_put(transport);
return 0;
}