From 9f4ab18ac51dc87345a9cbd2527e6acf7a0a9335 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Tue, 23 May 2017 16:48:36 -0700 Subject: xen/scsiback: Fix a TMR related use-after-free scsiback_release_cmd() must not dereference se_cmd->se_tmr_req because that memory is freed by target_free_cmd_mem() before scsiback_release_cmd() is called. Fix this use-after-free by inlining struct scsiback_tmr into struct vscsibk_pend. Signed-off-by: Bart Van Assche Reviewed-by: Juergen Gross Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: David Disseldorp Cc: xen-devel@lists.xenproject.org Cc: # 3.18+ Signed-off-by: Nicholas Bellinger --- drivers/xen/xen-scsiback.c | 33 +++++++++------------------------ 1 file changed, 9 insertions(+), 24 deletions(-) (limited to 'drivers/xen') diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c index d6950e0802b7..980f32817305 100644 --- a/drivers/xen/xen-scsiback.c +++ b/drivers/xen/xen-scsiback.c @@ -134,9 +134,7 @@ struct vscsibk_pend { struct page *pages[VSCSI_MAX_GRANTS]; struct se_cmd se_cmd; -}; -struct scsiback_tmr { atomic_t tmr_complete; wait_queue_head_t tmr_wait; }; @@ -599,26 +597,20 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req, struct scsiback_tpg *tpg = pending_req->v2p->tpg; struct scsiback_nexus *nexus = tpg->tpg_nexus; struct se_cmd *se_cmd = &pending_req->se_cmd; - struct scsiback_tmr *tmr; u64 unpacked_lun = pending_req->v2p->lun; int rc, err = FAILED; - tmr = kzalloc(sizeof(struct scsiback_tmr), GFP_KERNEL); - if (!tmr) { - target_put_sess_cmd(se_cmd); - goto err; - } - - init_waitqueue_head(&tmr->tmr_wait); + init_waitqueue_head(&pending_req->tmr_wait); rc = target_submit_tmr(&pending_req->se_cmd, nexus->tvn_se_sess, &pending_req->sense_buffer[0], - unpacked_lun, tmr, act, GFP_KERNEL, + unpacked_lun, NULL, act, GFP_KERNEL, tag, TARGET_SCF_ACK_KREF); if (rc) goto err; - wait_event(tmr->tmr_wait, atomic_read(&tmr->tmr_complete)); + wait_event(pending_req->tmr_wait, + atomic_read(&pending_req->tmr_complete)); err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ? SUCCESS : FAILED; @@ -626,9 +618,8 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req, scsiback_do_resp_with_sense(NULL, err, 0, pending_req); transport_generic_free_cmd(&pending_req->se_cmd, 1); return; + err: - if (tmr) - kfree(tmr); scsiback_do_resp_with_sense(NULL, err, 0, pending_req); } @@ -1389,12 +1380,6 @@ static int scsiback_check_stop_free(struct se_cmd *se_cmd) static void scsiback_release_cmd(struct se_cmd *se_cmd) { struct se_session *se_sess = se_cmd->se_sess; - struct se_tmr_req *se_tmr = se_cmd->se_tmr_req; - - if (se_tmr && se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) { - struct scsiback_tmr *tmr = se_tmr->fabric_tmr_ptr; - kfree(tmr); - } percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag); } @@ -1455,11 +1440,11 @@ static int scsiback_queue_status(struct se_cmd *se_cmd) static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd) { - struct se_tmr_req *se_tmr = se_cmd->se_tmr_req; - struct scsiback_tmr *tmr = se_tmr->fabric_tmr_ptr; + struct vscsibk_pend *pending_req = container_of(se_cmd, + struct vscsibk_pend, se_cmd); - atomic_set(&tmr->tmr_complete, 1); - wake_up(&tmr->tmr_wait); + atomic_set(&pending_req->tmr_complete, 1); + wake_up(&pending_req->tmr_wait); } static void scsiback_aborted_task(struct se_cmd *se_cmd) -- cgit v1.2.3-58-ga151 From e3eac12442c2678d64b655e9768bda1be65e0b68 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Tue, 23 May 2017 16:48:37 -0700 Subject: xen/scsiback: Replace a waitqueue and a counter by a completion This patch simplifies the implementation of the scsiback driver but does not change its behavior. Signed-off-by: Bart Van Assche Reviewed-by: Juergen Gross Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: David Disseldorp Cc: xen-devel@lists.xenproject.org Signed-off-by: Nicholas Bellinger --- drivers/xen/xen-scsiback.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) (limited to 'drivers/xen') diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c index 980f32817305..4cb33a0916a8 100644 --- a/drivers/xen/xen-scsiback.c +++ b/drivers/xen/xen-scsiback.c @@ -135,8 +135,7 @@ struct vscsibk_pend { struct se_cmd se_cmd; - atomic_t tmr_complete; - wait_queue_head_t tmr_wait; + struct completion tmr_done; }; #define VSCSI_DEFAULT_SESSION_TAGS 128 @@ -600,7 +599,7 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req, u64 unpacked_lun = pending_req->v2p->lun; int rc, err = FAILED; - init_waitqueue_head(&pending_req->tmr_wait); + init_completion(&pending_req->tmr_done); rc = target_submit_tmr(&pending_req->se_cmd, nexus->tvn_se_sess, &pending_req->sense_buffer[0], @@ -609,8 +608,7 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req, if (rc) goto err; - wait_event(pending_req->tmr_wait, - atomic_read(&pending_req->tmr_complete)); + wait_for_completion(&pending_req->tmr_done); err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ? SUCCESS : FAILED; @@ -1443,8 +1441,7 @@ static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd) struct vscsibk_pend *pending_req = container_of(se_cmd, struct vscsibk_pend, se_cmd); - atomic_set(&pending_req->tmr_complete, 1); - wake_up(&pending_req->tmr_wait); + complete(&pending_req->tmr_done); } static void scsiback_aborted_task(struct se_cmd *se_cmd) -- cgit v1.2.3-58-ga151 From af90e84d1f535827f4c593436a807b1efa9f6f2b Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Tue, 23 May 2017 16:48:38 -0700 Subject: xen/scsiback: Make TMF processing slightly faster Target drivers must guarantee that struct se_cmd and struct se_tmr_req exist as long as target_tmr_work() is in progress. Since the last access by the LIO core is a call to .check_stop_free() and since the Xen scsiback .check_stop_free() drops a reference to the TMF, it is already guaranteed that the struct se_cmd that corresponds to the TMF exists as long as target_tmr_work() is in progress. Hence change the second argument of transport_generic_free_cmd() from 1 into 0. Signed-off-by: Bart Van Assche Reviewed-by: Juergen Gross Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: David Disseldorp Cc: xen-devel@lists.xenproject.org Signed-off-by: Nicholas Bellinger --- drivers/xen/xen-scsiback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/xen') diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c index 4cb33a0916a8..7bc88fd43cfc 100644 --- a/drivers/xen/xen-scsiback.c +++ b/drivers/xen/xen-scsiback.c @@ -614,7 +614,7 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req, SUCCESS : FAILED; scsiback_do_resp_with_sense(NULL, err, 0, pending_req); - transport_generic_free_cmd(&pending_req->se_cmd, 1); + transport_generic_free_cmd(&pending_req->se_cmd, 0); return; err: -- cgit v1.2.3-58-ga151