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| author | Nicholas Bellinger <nab@linux-iscsi.org> | 2015-07-22 00:24:09 -0700 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2015-08-27 13:25:51 -0400 |
| commit | 118f2fd7d58df44c3bf830868d70e952ad0d4ecb (patch) | |
| tree | b97e49a8097a3c78d4e8069fcf197636e87b897c | |
| parent | b332d923c390c581ba3498d136bfb5127b67d76a (diff) | |
| download | lwn-118f2fd7d58df44c3bf830868d70e952ad0d4ecb.tar.gz lwn-118f2fd7d58df44c3bf830868d70e952ad0d4ecb.zip | |
iscsi-target: Fix use-after-free during TPG session shutdown
[ Upstream commit 417c20a9bdd1e876384127cf096d8ae8b559066c ]
This patch fixes a use-after-free bug in iscsit_release_sessions_for_tpg()
where se_portal_group->session_lock was incorrectly released/re-acquired
while walking the active se_portal_group->tpg_sess_list.
The can result in a NULL pointer dereference when iscsit_close_session()
shutdown happens in the normal path asynchronously to this code, causing
a bogus dereference of an already freed list entry to occur.
To address this bug, walk the session list checking for the same state
as before, but move entries to a local list to avoid dropping the lock
while walking the active list.
As before, signal using iscsi_session->session_restatement=1 for those
list entries to be released locally by iscsit_free_session() code.
Reported-by: Sunilkumar Nadumuttlu <sjn@datera.io>
Cc: Sunilkumar Nadumuttlu <sjn@datera.io>
Cc: <stable@vger.kernel.org> # v3.1+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
| -rw-r--r-- | drivers/target/iscsi/iscsi_target.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index 3c5dd9762476..ffc25cbdf50c 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -4732,6 +4732,7 @@ int iscsit_release_sessions_for_tpg(struct iscsi_portal_group *tpg, int force) struct iscsi_session *sess; struct se_portal_group *se_tpg = &tpg->tpg_se_tpg; struct se_session *se_sess, *se_sess_tmp; + LIST_HEAD(free_list); int session_count = 0; spin_lock_bh(&se_tpg->session_lock); @@ -4753,14 +4754,17 @@ int iscsit_release_sessions_for_tpg(struct iscsi_portal_group *tpg, int force) } atomic_set(&sess->session_reinstatement, 1); spin_unlock(&sess->conn_lock); - spin_unlock_bh(&se_tpg->session_lock); - iscsit_free_session(sess); - spin_lock_bh(&se_tpg->session_lock); + list_move_tail(&se_sess->sess_list, &free_list); + } + spin_unlock_bh(&se_tpg->session_lock); + list_for_each_entry_safe(se_sess, se_sess_tmp, &free_list, sess_list) { + sess = (struct iscsi_session *)se_sess->fabric_sess_ptr; + + iscsit_free_session(sess); session_count++; } - spin_unlock_bh(&se_tpg->session_lock); pr_debug("Released %d iSCSI Session(s) from Target Portal" " Group: %hu\n", session_count, tpg->tpgt); |