From ddc10938e08cd7aac63d8385f7305f7889df5179 Mon Sep 17 00:00:00 2001
From: Bjorn Helgaas <bhelgaas@google.com>
Date: Fri, 16 Dec 2022 10:21:26 -0600
Subject: [PATCH] PCI: switchtec: Return -EFAULT for copy_to_user() errors
Git-commit: ddc10938e08cd7aac63d8385f7305f7889df5179
Patch-mainline: v6.3-rc1
References: git-fixes

switchtec_dev_read() didn't handle copy_to_user() errors correctly: it
assigned "rc = -EFAULT", but actually returned either "size", -ENXIO, or
-EBADMSG instead.

Update the failure cases to unlock mrpc_mutex and return -EFAULT directly.

Link: https://lore.kernel.org/r/20221216162126.207863-3-helgaas@kernel.org
Fixes: 080b47def5e5 ("MicroSemi Switchtec management interface driver")
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/pci/switch/switchtec.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -552,21 +552,20 @@ static ssize_t switchtec_dev_read(struct
 	rc = copy_to_user(data, &stuser->return_code,
 			  sizeof(stuser->return_code));
 	if (rc) {
-		rc = -EFAULT;
-		goto out;
+		mutex_unlock(&stdev->mrpc_mutex);
+		return -EFAULT;
 	}
 
 	data += sizeof(stuser->return_code);
 	rc = copy_to_user(data, &stuser->data,
 			  size - sizeof(stuser->return_code));
 	if (rc) {
-		rc = -EFAULT;
-		goto out;
+		mutex_unlock(&stdev->mrpc_mutex);
+		return -EFAULT;
 	}
 
 	stuser_set_state(stuser, MRPC_IDLE);
 
-out:
 	mutex_unlock(&stdev->mrpc_mutex);
 
 	if (stuser->status == SWITCHTEC_MRPC_STATUS_DONE)