This is a note to let you know that I've just added the patch titled
scsi: target: iscsi: Prevent login threads from racing between each other
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
scsi-target-iscsi-prevent-login-threads-from-racing-.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0eb67a16083d23be4368aeaf535b8d5482b5a62f
Author: Maurizio Lombardi <mlombard@xxxxxxxxxx>
Date: Mon May 8 18:22:19 2023 +0200
scsi: target: iscsi: Prevent login threads from racing between each other
[ Upstream commit 2a737d3b8c792400118d6cf94958f559de9c5e59 ]
The tpg->np_login_sem is a semaphore that is used to serialize the login
process when multiple login threads run concurrently against the same
target portal group.
The iscsi_target_locate_portal() function finds the tpg, calls
iscsit_access_np() against the np_login_sem semaphore and saves the tpg
pointer in conn->tpg;
If iscsi_target_locate_portal() fails, the caller will check for the
conn->tpg pointer and, if it's not NULL, then it will assume that
iscsi_target_locate_portal() called iscsit_access_np() on the semaphore.
Make sure that conn->tpg gets initialized only if iscsit_access_np() was
successful, otherwise iscsit_deaccess_np() may end up being called against
a semaphore we never took, allowing more than one thread to access the same
tpg.
Signed-off-by: Maurizio Lombardi <mlombard@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230508162219.1731964-4-mlombard@xxxxxxxxxx
Reviewed-by: Mike Christie <michael.christie@xxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index 5db8842a80265..e39177f9fdb0a 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -1072,6 +1072,7 @@ int iscsi_target_locate_portal(
iscsi_target_set_sock_callbacks(conn);
login->np = np;
+ conn->tpg = NULL;
login_req = (struct iscsi_login_req *) login->req;
payload_length = ntoh24(login_req->dlength);
@@ -1141,7 +1142,6 @@ int iscsi_target_locate_portal(
*/
sessiontype = strncmp(s_buf, DISCOVERY, 9);
if (!sessiontype) {
- conn->tpg = iscsit_global->discovery_tpg;
if (!login->leading_connection)
goto get_target;
@@ -1158,9 +1158,11 @@ int iscsi_target_locate_portal(
* Serialize access across the discovery struct iscsi_portal_group to
* process login attempt.
*/
+ conn->tpg = iscsit_global->discovery_tpg;
if (iscsit_access_np(np, conn->tpg) < 0) {
iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
ISCSI_LOGIN_STATUS_SVC_UNAVAILABLE);
+ conn->tpg = NULL;
ret = -1;
goto out;
}
