[PATCH AUTOSEL 5.18 037/159] scsi: lpfc: Fix null pointer dereference after failing to issue FLOGI and PLOGI

Sasha Levin
2022-05-30T13:28:38Z

From: James Smart <jsmart2021@gmail.com>

[ Upstream commit 577a942df3de2666f6947bdd3a5c9e8d30073424 ]

If lpfc_issue_els_flogi() fails and returns non-zero status, the node
reference count is decremented to trigger the release of the nodelist
structure. However, if there is a prior registration or dev-loss-evt work
pending, the node may be released prematurely. When dev-loss-evt
completes, the released node is referenced causing a use-after-free null
pointer dereference.

Similarly, when processing non-zero ELS PLOGI completion status in
lpfc_cmpl_els_plogi(), the ndlp flags are checked for a transport
registration before triggering node removal. If dev-loss-evt work is
pending, the node may be released prematurely and a subsequent call to
lpfc_dev_loss_tmo_handler() results in a use after free ndlp dereference.

Add test for pending dev-loss before decrementing the node reference count
for FLOGI, PLOGI, PRLI, and ADISC handling.

Link: https://lore.kernel.org/r/20220412222008.126521-9-jsmart2021@gmail.com
Co-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/lpfc/lpfc_els.c | 51 +++++++++++++++++++++++++-----------
1 file changed, 35 insertions(+), 16 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_els.c b/drivers/scsi/lpfc/lpfc_els.c
index 872a26376ccb..46a01a51b207 100644
--- a/drivers/scsi/lpfc/lpfc_els.c
+++ b/drivers/scsi/lpfc/lpfc_els.c
@@ -1532,10 +1532,13 @@ lpfc_initial_flogi(struct lpfc_vport *vport)
}

if (lpfc_issue_els_flogi(vport, ndlp, 0)) {
- /* This decrement of reference count to node shall kick off
- * the release of the node.
+ /* A node reference should be retained while registered with a
+ * transport or dev-loss-evt work is pending.
+ * Otherwise, decrement node reference to trigger release.
*/
- lpfc_nlp_put(ndlp);
+ if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD)) &&
+ !(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+ lpfc_nlp_put(ndlp);
return 0;
}
return 1;
@@ -1578,10 +1581,13 @@ lpfc_initial_fdisc(struct lpfc_vport *vport)
}

if (lpfc_issue_els_fdisc(vport, ndlp, 0)) {
- /* decrement node reference count to trigger the release of
- * the node.
+ /* A node reference should be retained while registered with a
+ * transport or dev-loss-evt work is pending.
+ * Otherwise, decrement node reference to trigger release.
*/
- lpfc_nlp_put(ndlp);
+ if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD)) &&
+ !(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+ lpfc_nlp_put(ndlp);
return 0;
}
return 1;
@@ -1983,6 +1989,7 @@ lpfc_cmpl_els_plogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
int disc;
struct serv_parm *sp = NULL;
u32 ulp_status, ulp_word4, did, iotag;
+ bool release_node = false;

/* we pass cmdiocb to state machine which needs rspiocb as well */
cmdiocb->context_un.rsp_iocb = rspiocb;
@@ -2071,19 +2078,21 @@ lpfc_cmpl_els_plogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
spin_unlock_irq(&ndlp->lock);
goto out;
}
- spin_unlock_irq(&ndlp->lock);

/* No PLOGI collision and the node is not registered with the
* scsi or nvme transport. It is no longer an active node. Just
* start the device remove process.
*/
if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD))) {
- spin_lock_irq(&ndlp->lock);
ndlp->nlp_flag &= ~NLP_NPR_2B_DISC;
- spin_unlock_irq(&ndlp->lock);
+ if (!(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+ release_node = true;
+ }
+ spin_unlock_irq(&ndlp->lock);
+
+ if (release_node)
lpfc_disc_state_machine(vport, ndlp, cmdiocb,
NLP_EVT_DEVICE_RM);
- }
} else {
/* Good status, call state machine */
prsp = list_entry(((struct lpfc_dmabuf *)
@@ -2294,6 +2303,7 @@ lpfc_cmpl_els_prli(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
u32 loglevel;
u32 ulp_status;
u32 ulp_word4;
+ bool release_node = false;

/* we pass cmdiocb to state machine which needs rspiocb as well */
cmdiocb->context_un.rsp_iocb = rspiocb;
@@ -2370,14 +2380,18 @@ lpfc_cmpl_els_prli(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
* it is no longer an active node. Otherwise devloss
* handles the final cleanup.
*/
+ spin_lock_irq(&ndlp->lock);
if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD)) &&
!ndlp->fc4_prli_sent) {
- spin_lock_irq(&ndlp->lock);
ndlp->nlp_flag &= ~NLP_NPR_2B_DISC;
- spin_unlock_irq(&ndlp->lock);
+ if (!(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+ release_node = true;
+ }
+ spin_unlock_irq(&ndlp->lock);
+
+ if (release_node)
lpfc_disc_state_machine(vport, ndlp, cmdiocb,
NLP_EVT_DEVICE_RM);
- }
} else {
/* Good status, call state machine. However, if another
* PRLI is outstanding, don't call the state machine
@@ -2749,6 +2763,7 @@ lpfc_cmpl_els_adisc(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
struct lpfc_nodelist *ndlp;
int disc;
u32 ulp_status, ulp_word4, tmo;
+ bool release_node = false;

/* we pass cmdiocb to state machine which needs rspiocb as well */
cmdiocb->context_un.rsp_iocb = rspiocb;
@@ -2815,13 +2830,17 @@ lpfc_cmpl_els_adisc(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
* transport, it is no longer an active node. Otherwise
* devloss handles the final cleanup.
*/
+ spin_lock_irq(&ndlp->lock);
if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD))) {
- spin_lock_irq(&ndlp->lock);
ndlp->nlp_flag &= ~NLP_NPR_2B_DISC;
- spin_unlock_irq(&ndlp->lock);
+ if (!(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+ release_node = true;
+ }
+ spin_unlock_irq(&ndlp->lock);
+
+ if (release_node)
lpfc_disc_state_machine(vport, ndlp, cmdiocb,
NLP_EVT_DEVICE_RM);
- }
} else
/* Good status, call state machine */
lpfc_disc_state_machine(vport, ndlp, cmdiocb,
--
2.35.1