scsi: lpfc: Fix use-after-free KFENCE violation during sysfs firmware write

During the sysfs firmware write process, a use-after-free read warning is
logged from the lpfc_wr_object() routine:

  BUG: KFENCE: use-after-free read in lpfc_wr_object+0x235/0x310 [lpfc]
  Use-after-free read at 0x0000000000cf164d (in kfence-#111):
  lpfc_wr_object+0x235/0x310 [lpfc]
  lpfc_write_firmware.cold+0x206/0x30d [lpfc]
  lpfc_sli4_request_firmware_update+0xa6/0x100 [lpfc]
  lpfc_request_firmware_upgrade_store+0x66/0xb0 [lpfc]
  kernfs_fop_write_iter+0x121/0x1b0
  new_sync_write+0x11c/0x1b0
  vfs_write+0x1ef/0x280
  ksys_write+0x5f/0xe0
  do_syscall_64+0x59/0x90
  entry_SYSCALL_64_after_hwframe+0x63/0xcd

The driver accessed wr_object pointer data, which was initialized into
mailbox payload memory, after the mailbox object was released back to the
mailbox pool.

Fix by moving the mailbox free calls to the end of the routine ensuring
that we don't reference internal mailbox memory after release.

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index c21187c93a5f..55dfab9ae3c9 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -20815,6 +20815,7 @@ lpfc_wr_object(struct lpfc_hba *phba, struct list_head *dmabuf_list,
 	struct lpfc_mbx_wr_object *wr_object;
 	LPFC_MBOXQ_t *mbox;
 	int rc = 0, i = 0;
+	int mbox_status = 0;
 	uint32_t shdr_status, shdr_add_status, shdr_add_status_2;
 	uint32_t shdr_change_status = 0, shdr_csf = 0;
 	uint32_t mbox_tmo;
@@ -20860,11 +20861,15 @@ lpfc_wr_object(struct lpfc_hba *phba, struct list_head *dmabuf_list,
 	wr_object->u.request.bde_count = i;
 	bf_set(lpfc_wr_object_write_length, &wr_object->u.request, written);
 	if (!phba->sli4_hba.intr_enable)
-		rc = lpfc_sli_issue_mbox(phba, mbox, MBX_POLL);
+		mbox_status = lpfc_sli_issue_mbox(phba, mbox, MBX_POLL);
 	else {
 		mbox_tmo = lpfc_mbox_tmo_val(phba, mbox);
-		rc = lpfc_sli_issue_mbox_wait(phba, mbox, mbox_tmo);
+		mbox_status = lpfc_sli_issue_mbox_wait(phba, mbox, mbox_tmo);
 	}
+
+	/* The mbox status needs to be maintained to detect MBOX_TIMEOUT. */
+	rc = mbox_status;
+
 	/* The IOCTL status is embedded in the mailbox subheader. */
 	shdr_status = bf_get(lpfc_mbox_hdr_status,
 			     &wr_object->header.cfg_shdr.response);
@@ -20879,10 +20884,6 @@ lpfc_wr_object(struct lpfc_hba *phba, struct list_head *dmabuf_list,
 				  &wr_object->u.response);
 	}
 
-	if (!phba->sli4_hba.intr_enable)
-		mempool_free(mbox, phba->mbox_mem_pool);
-	else if (rc != MBX_TIMEOUT)
-		mempool_free(mbox, phba->mbox_mem_pool);
 	if (shdr_status || shdr_add_status || shdr_add_status_2 || rc) {
 		lpfc_printf_log(phba, KERN_ERR, LOG_TRACE_EVENT,
 				"3025 Write Object mailbox failed with "
@@ -20900,6 +20901,12 @@ lpfc_wr_object(struct lpfc_hba *phba, struct list_head *dmabuf_list,
 		lpfc_log_fw_write_cmpl(phba, shdr_status, shdr_add_status,
 				       shdr_add_status_2, shdr_change_status,
 				       shdr_csf);
+
+	if (!phba->sli4_hba.intr_enable)
+		mempool_free(mbox, phba->mbox_mem_pool);
+	else if (mbox_status != MBX_TIMEOUT)
+		mempool_free(mbox, phba->mbox_mem_pool);
+
 	return rc;
 }