[PATCH v2 07/16] lpfc: Fix use-after-free on unused nodes after port swap

From: James Smart <jsmart2021@gmail.com>
To: linux-scsi@vger.kernel.org
Cc: James Smart <jsmart2021@gmail.com>, Justin Tee <justin.tee@broadcom.com>
Subject: [PATCH v2 07/16] lpfc: Fix use-after-free on unused nodes after port swap
Date: Sun, 11 Apr 2021 18:31:18 -0700	[thread overview]
Message-ID: <20210412013127.2387-8-jsmart2021@gmail.com> (raw)
In-Reply-To: <20210412013127.2387-1-jsmart2021@gmail.com>

During target port swap, the swap logic ignores the DROPPED flag in
the nodes. As a node then moves into the UNUSED state, the reference
count will be dropped. If a node is later reused and moved out of the
UNUSED state, an access can result in a use-after-free assert.

Fix by having the port swap logic propagate the DROPPED flag when
switching nodes. This will avoid reference from being dropped.

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>
---
 drivers/scsi/lpfc/lpfc_els.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/scsi/lpfc/lpfc_els.c b/drivers/scsi/lpfc/lpfc_els.c
index ed57d92e96e1..c919bedd931c 100644
--- a/drivers/scsi/lpfc/lpfc_els.c
+++ b/drivers/scsi/lpfc/lpfc_els.c
@@ -1691,6 +1691,15 @@ lpfc_plogi_confirm_nport(struct lpfc_hba *phba, uint32_t *prsp,
 	else
 		new_ndlp->nlp_flag &= ~NLP_RPI_REGISTERED;
 
+	/*
+	 * Retain the DROPPED flag. This will take care of the init
+	 * refcount when affecting the state change
+	 */
+	if (keep_new_nlp_flag & NLP_DROPPED)
+		new_ndlp->nlp_flag |= NLP_DROPPED;
+	else
+		new_ndlp->nlp_flag &= ~NLP_DROPPED;
+
 	ndlp->nlp_flag = keep_new_nlp_flag;
 
 	/* if ndlp had NLP_UNREG_INP set, keep it */
@@ -1705,6 +1714,15 @@ lpfc_plogi_confirm_nport(struct lpfc_hba *phba, uint32_t *prsp,
 	else
 		ndlp->nlp_flag &= ~NLP_RPI_REGISTERED;
 
+	/*
+	 * Retain the DROPPED flag. This will take care of the init
+	 * refcount when affecting the state change
+	 */
+	if (keep_nlp_flag & NLP_DROPPED)
+		ndlp->nlp_flag |= NLP_DROPPED;
+	else
+		ndlp->nlp_flag &= ~NLP_DROPPED;
+
 	spin_unlock_irq(&new_ndlp->lock);
 	spin_unlock_irq(&ndlp->lock);
 
-- 
2.26.2

