scsi: sg: add sg_remove_request in sg_write

mainline inclusion
from mainline-v5.7-rc3
commit 83c6f239
category: bugfix
bugzilla: 13690
CVE: CVE-2020-12770

-------------------------------------------------

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

Link: https://lore.kernel.org/r/610618d9-e983-fd56-ed0f-639428343af7@huawei.comAcked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NWu Bo <wubo40@huawei.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Conflicts:
  drivers/scsi/sg.c
[yyl: adjust context]
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/scsi/sg.c

@@ -694,8 +694,10 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
 	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