diff options
| author | Hannes Reinecke <hare@suse.de> | 2016-08-22 10:54:07 +0200 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2016-10-21 01:19:41 -0700 |
| commit | 1b4c59b7a1d0b9d8019254a5f2e35b2663f49a9e (patch) | |
| tree | 205b14587942953e85ff09798ac87d7ce1497f30 | |
| parent | 61f36166c245e563c7a2b624f4c78c5ce0f680d6 (diff) | |
target: fix potential race window in target_sess_cmd_list_waiting()
target_sess_cmd_list_waiting() might hit on a condition where
the kref for the command is already 0, but the destructor has
not been called yet (or is stuck in waiting for a spin lock).
Rather than leaving the command on the list we should explicitly
remove it to avoid race issues later on.
Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
| -rw-r--r-- | drivers/target/target_core_transport.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index e825d580ccee..7dfefd66df93 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -2535,7 +2535,9 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref) * invocations before se_cmd descriptor release. */ if (ack_kref) { - kref_get(&se_cmd->cmd_kref); + if (!kref_get_unless_zero(&se_cmd->cmd_kref)) + return -EINVAL; + se_cmd->se_cmd_flags |= SCF_ACK_KREF; } @@ -2616,7 +2618,7 @@ EXPORT_SYMBOL(target_put_sess_cmd); */ void target_sess_cmd_list_set_waiting(struct se_session *se_sess) { - struct se_cmd *se_cmd; + struct se_cmd *se_cmd, *tmp_cmd; unsigned long flags; int rc; @@ -2628,14 +2630,16 @@ void target_sess_cmd_list_set_waiting(struct se_session *se_sess) se_sess->sess_tearing_down = 1; list_splice_init(&se_sess->sess_cmd_list, &se_sess->sess_wait_list); - list_for_each_entry(se_cmd, &se_sess->sess_wait_list, se_cmd_list) { + list_for_each_entry_safe(se_cmd, tmp_cmd, + &se_sess->sess_wait_list, se_cmd_list) { rc = kref_get_unless_zero(&se_cmd->cmd_kref); if (rc) { se_cmd->cmd_wait_set = 1; spin_lock(&se_cmd->t_state_lock); se_cmd->transport_state |= CMD_T_FABRIC_STOP; spin_unlock(&se_cmd->t_state_lock); - } + } else + list_del_init(&se_cmd->se_cmd_list); } spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); |