git: 6cdff09c0d70 - main - gntdev: Handle errors from suword32() in gntdev_alloc_gref()

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=6cdff09c0d70f780a738dbd3d87deb3b13ec8446

commit 6cdff09c0d70f780a738dbd3d87deb3b13ec8446
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2023-12-26 01:42:58 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2023-12-26 02:04:01 +0000

    gntdev: Handle errors from suword32() in gntdev_alloc_gref()
    
    Try to copy out output values before handling errors, and check that we
    did so successfully.  In particular, it doesn't seem sensible to ignore
    errors here, otherwise userspace won't have any way to refer to the
    allocations.
    
    This is in preparation for annotating copyin() and related functions
    with __result_use_check.
    
    Reviewed by:    royger
    MFC after:      1 week
    Differential Revision:  https://reviews.freebsd.org/D43145
---
 sys/dev/xen/gntdev/gntdev.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/sys/dev/xen/gntdev/gntdev.c b/sys/dev/xen/gntdev/gntdev.c
index a9b69ba1605e..4530feb1c76d 100644
--- a/sys/dev/xen/gntdev/gntdev.c
+++ b/sys/dev/xen/gntdev/gntdev.c
@@ -383,6 +383,13 @@ gntdev_alloc_gref(struct ioctl_gntdev_alloc_gref *arg)
 		}
 	}
 
+	/* Copy the output values. */
+	arg->index = file_offset;
+	for (i = 0; error == 0 && i < arg->count; i++) {
+		if (suword32(&arg->gref_ids[i], grefs[i].gref_id) != 0)
+			error = EFAULT;
+	}
+
 	if (error != 0) {
 		/*
 		 * If target domain maps the gref (by guessing the gref-id),
@@ -401,11 +408,6 @@ gntdev_alloc_gref(struct ioctl_gntdev_alloc_gref *arg)
 		return (error);
 	}
 
-	/* Copy the output values. */
-	arg->index = file_offset;
-	for (i = 0; i < arg->count; i++)
-		suword32(&arg->gref_ids[i], grefs[i].gref_id);
-
 	/* Modify the per user private data. */
 	mtx_lock(&priv_user->user_data_lock);
 	for (i = 0; i < arg->count; i++)