From: Wu Bo <wubo40@huawei.com>
Date: Tue, 14 Apr 2020 10:13:28 +0800
Subject: scsi: sg: add sg_remove_request in sg_write
Git-commit: 83c6f2390040f188cc25b270b4befeb5628c1aee
Patch-mainline: v5.7-rc3
References: bsc#1171420 CVE-2020-12770

If the __copy_from_user function failed we need to call sg_remove_request
in sg_write.

[lduncan: modified since we are still using __copy_from_user()]

Link: https://lore.kernel.org/r/610618d9-e983-fd56-ed0f-639428343af7@huawei.com
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Wu Bo <wubo40@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/scsi/sg.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -695,8 +695,10 @@ sg_write(struct file *filp, const char _
 	hp->flags = input_size;	/* structure abuse ... */
 	hp->pack_id = old_hdr.pack_id;
 	hp->usr_ptr = NULL;
-	if (__copy_from_user(cmnd, buf, cmd_size))
+	if (__copy_from_user(cmnd, buf, cmd_size)) {
+		sg_remove_request(sfp, srp);
 		return -EFAULT;
+	}
 	/*
 	 * SG_DXFER_TO_FROM_DEV is functionally equivalent to SG_DXFER_FROM_DEV,
 	 * but is is possible that the app intended SG_DXFER_TO_DEV, because there