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FAILED: patch "[PATCH] scsi: lpfc: Fix buffer free/clear order in deferred receive" failed to apply to 5.4-stable tree

PATCH New [email protected] 2 participants 2 messages Sep 6, 2025 – Sep 7, 2025

Subsystems (3)
Stable branch SCSI Emulex/Broadcom lpfc FC/FCoE SCSI driver
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[email protected]

author maintainer
#0 lore raw

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 9dba9a45c348e8460da97c450cddf70b2056deb3
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025090623-retiring-only-9b80@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9dba9a45c348e8460da97c450cddf70b2056deb3 Mon Sep 17 00:00:00 2001
From: John Evans <[email protected]>
Date: Thu, 28 Aug 2025 12:40:08 +0800
Subject: [PATCH] scsi: lpfc: Fix buffer free/clear order in deferred receive
path

Fix a use-after-free window by correcting the buffer release sequence in the deferred receive path. The code freed the RQ buffer first and only then cleared the context pointer under the lock. Concurrent paths (e.g., ABTS and the repost path) also inspect and release the same pointer under the lock, so the old order could lead to double-free/UAF.

Note that the repost path already uses the correct pattern: detach the pointer under the lock, then free it after dropping the lock. The deferred path should do the same.

Fixes 472e146d1cf3 ("scsi: lpfc: Correct upcalling nvmet_fc transport during io done downcall")
Cc [email protected]
Signed-off-by John Evans <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Reviewed-by Justin Tee <[email protected]>
Signed-off-by Martin K. Petersen <[email protected]>
drivers/scsi/lpfc/lpfc_nvmet.c +6 -4
index fba2e62027b7..4cfc928bcf2d 100644
@@ -1243,7 +1243,7 @@ lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
 	struct lpfc_nvmet_tgtport *tgtp;
 	struct lpfc_async_xchg_ctx *ctxp =
 		container_of(rsp, struct lpfc_async_xchg_ctx, hdlrctx.fcp_req);
-	struct rqb_dmabuf *nvmebuf = ctxp->rqb_buffer;
+	struct rqb_dmabuf *nvmebuf;
 	struct lpfc_hba *phba = ctxp->phba;
 	unsigned long iflag;
 

@@ -1251,13 +1251,18 @@ lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
 	lpfc_nvmeio_data(phba, "NVMET DEFERRCV: xri x%x sz %d CPU %02x\n",
 			 ctxp->oxid, ctxp->size, raw_smp_processor_id());
 
+	spin_lock_irqsave(&ctxp->ctxlock, iflag);
+	nvmebuf = ctxp->rqb_buffer;
 	if (!nvmebuf) {
+		spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
 		lpfc_printf_log(phba, KERN_INFO, LOG_NVME_IOERR,
 				"6425 Defer rcv: no buffer oxid x%x: "
 				"flg %x ste %x\n",
 				ctxp->oxid, ctxp->flag, ctxp->state);
 		return;
 	}
+	ctxp->rqb_buffer = NULL;
+	spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
 
 	tgtp = phba->targetport->private;
 	if (tgtp)

@@ -1265,9 +1270,6 @@ lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
 
 	/* Free the nvmebuf since a new buffer already replaced it */
 	nvmebuf->hrq->rqbp->rqb_free_buffer(phba, nvmebuf);
-	spin_lock_irqsave(&ctxp->ctxlock, iflag);
-	ctxp->rqb_buffer = NULL;
-	spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
 }
 
 /**
maintainer
#1 lore raw

PATCH 1/1 scsi: lpfc: Fix buffer free/clear order in deferred receive path

From: John Evans <[email protected]>

[ Upstream commit 9dba9a45c348e8460da97c450cddf70b2056deb3 ]

Fix a use-after-free window by correcting the buffer release sequence in the deferred receive path. The code freed the RQ buffer first and only then cleared the context pointer under the lock. Concurrent paths (e.g., ABTS and the repost path) also inspect and release the same pointer under the lock, so the old order could lead to double-free/UAF.

Note that the repost path already uses the correct pattern: detach the pointer under the lock, then free it after dropping the lock. The deferred path should do the same.

Fixes 472e146d1cf3 ("scsi: lpfc: Correct upcalling nvmet_fc transport during io done downcall")
Cc [email protected]
Signed-off-by John Evans <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Reviewed-by Justin Tee <[email protected]>
Signed-off-by Martin K. Petersen <[email protected]>
[ Adjust context ]
Signed-off-by Sasha Levin <[email protected]>
---
 drivers/scsi/lpfc/lpfc_nvmet.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
drivers/scsi/lpfc/lpfc_nvmet.c +6 -4
index 979a6d11b1b71..728ec3f47e023 100644
@@ -1172,7 +1172,7 @@ lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
 	struct lpfc_nvmet_tgtport *tgtp;
 	struct lpfc_nvmet_rcv_ctx *ctxp =
 		container_of(rsp, struct lpfc_nvmet_rcv_ctx, ctx.fcp_req);
-	struct rqb_dmabuf *nvmebuf = ctxp->rqb_buffer;
+	struct rqb_dmabuf *nvmebuf;
 	struct lpfc_hba *phba = ctxp->phba;
 	unsigned long iflag;
 

@@ -1180,13 +1180,18 @@ lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
 	lpfc_nvmeio_data(phba, "NVMET DEFERRCV: xri x%x sz %d CPU %02x\n",
 			 ctxp->oxid, ctxp->size, raw_smp_processor_id());
 
+	spin_lock_irqsave(&ctxp->ctxlock, iflag);
+	nvmebuf = ctxp->rqb_buffer;
 	if (!nvmebuf) {
+		spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
 		lpfc_printf_log(phba, KERN_INFO, LOG_NVME_IOERR,
 				"6425 Defer rcv: no buffer oxid x%x: "
 				"flg %x ste %x\n",
 				ctxp->oxid, ctxp->flag, ctxp->state);
 		return;
 	}
+	ctxp->rqb_buffer = NULL;
+	spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
 
 	tgtp = phba->targetport->private;
 	if (tgtp)

@@ -1194,9 +1199,6 @@ lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
 
 	/* Free the nvmebuf since a new buffer already replaced it */
 	nvmebuf->hrq->rqbp->rqb_free_buffer(phba, nvmebuf);
-	spin_lock_irqsave(&ctxp->ctxlock, iflag);
-	ctxp->rqb_buffer = NULL;
-	spin_unlock_irqrestore(&ctxp->ctxlock, iflag);
 }
 
 static void
Signature · 1 line
2.51.0