| Message ID | 161248539022.21478.17038123892954492263.stgit@noble1 (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Fix some seq_file users that were recently broken | expand |
On Fri, Feb 05, 2021 at 11:36:30AM +1100, NeilBrown wrote: > 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 1f4aace60b0e ("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: 1f4aace60b0e ("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>
diff --git a/net/sctp/proc.c b/net/sctp/proc.c index f7da88ae20a5..982a87b3e11f 100644 --- a/net/sctp/proc.c +++ b/net/sctp/proc.c @@ -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; }
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 1f4aace60b0e ("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: 1f4aace60b0e ("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> --- net/sctp/proc.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)