From 2dfa6688aafdc3f74efeb1cf05fb871465d67f79 Mon Sep 17 00:00:00 2001 From: Steffen Maier Date: Wed, 8 Feb 2017 15:34:22 +0100 Subject: [PATCH] scsi: zfcp: fix use-after-free by not tracing WKA port open/close on failed send Dan Carpenter kindly reported: The patch d27a7cb91960: "zfcp: trace on request for open and close of WKA port" from Aug 10, 2016, leads to the following static checker warning: drivers/s390/scsi/zfcp_fsf.c:1615 zfcp_fsf_open_wka_port() warn: 'req' was already freed. drivers/s390/scsi/zfcp_fsf.c 1609 zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT); 1610 retval = zfcp_fsf_req_send(req); 1611 if (retval) 1612 zfcp_fsf_req_free(req); ^^^ Freed. 1613 out: 1614 spin_unlock_irq(&qdio->req_q_lock); 1615 if (req && !IS_ERR(req)) 1616 zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id); ^^^^^^^^^^^ Use after free. 1617 return retval; 1618 } Same thing for zfcp_fsf_close_wka_port() as well. Rather than relying on req being NULL (or ERR_PTR) for all cases where we don't want to trace or should not trace, simply check retval which is unconditionally initialized with -EIO != 0 and it can only become 0 on successful retval = zfcp_fsf_req_send(req). With that we can also remove the then again unnecessary unconditional initialization of req which was introduced with that earlier commit. Reported-by: Dan Carpenter Suggested-by: Benjamin Block Signed-off-by: Steffen Maier Fixes: d27a7cb91960 ("zfcp: trace on request for open and close of WKA port") Cc: #2.6.38+ Reviewed-by: Benjamin Block Reviewed-by: Jens Remus Signed-off-by: Martin K. Petersen --- drivers/s390/scsi/zfcp_fsf.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c index 75f820ca17b7..27ff38f839fc 100644 --- a/drivers/s390/scsi/zfcp_fsf.c +++ b/drivers/s390/scsi/zfcp_fsf.c @@ -1583,7 +1583,7 @@ out: int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port) { struct zfcp_qdio *qdio = wka_port->adapter->qdio; - struct zfcp_fsf_req *req = NULL; + struct zfcp_fsf_req *req; int retval = -EIO; spin_lock_irq(&qdio->req_q_lock); @@ -1612,7 +1612,7 @@ int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port) zfcp_fsf_req_free(req); out: spin_unlock_irq(&qdio->req_q_lock); - if (req && !IS_ERR(req)) + if (!retval) zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id); return retval; } @@ -1638,7 +1638,7 @@ static void zfcp_fsf_close_wka_port_handler(struct zfcp_fsf_req *req) int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port) { struct zfcp_qdio *qdio = wka_port->adapter->qdio; - struct zfcp_fsf_req *req = NULL; + struct zfcp_fsf_req *req; int retval = -EIO; spin_lock_irq(&qdio->req_q_lock); @@ -1667,7 +1667,7 @@ int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port) zfcp_fsf_req_free(req); out: spin_unlock_irq(&qdio->req_q_lock); - if (req && !IS_ERR(req)) + if (!retval) zfcp_dbf_rec_run_wka("fscwp_1", wka_port, req->req_id); return retval; }