Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933934AbbHJKh0 (ORCPT ); Mon, 10 Aug 2015 06:37:26 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:44003 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933935AbbHJKQb (ORCPT ); Mon, 10 Aug 2015 06:16:31 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Sunilkumar Nadumuttlu" , "Nicholas Bellinger" Date: Mon, 10 Aug 2015 12:12:31 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 104/110] iscsi-target: Fix use-after-free during TPG session shutdown In-Reply-To: X-SA-Exim-Connect-IP: 2.173.94.72 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2557 Lines: 69 3.2.71-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Bellinger commit 417c20a9bdd1e876384127cf096d8ae8b559066c upstream. 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 Cc: Sunilkumar Nadumuttlu Signed-off-by: Nicholas Bellinger Signed-off-by: Ben Hutchings --- drivers/target/iscsi/iscsi_target.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -4509,6 +4509,7 @@ int iscsit_release_sessions_for_tpg(stru 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); @@ -4530,14 +4531,17 @@ int iscsit_release_sessions_for_tpg(stru } 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/