linux-kernel - [PATCH 4.4 097/113] VT_RESIZEX: get rid of field-by-field copyin

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Date:   Thu, 27 Feb 2020 14:36:53 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 097/113] VT_RESIZEX: get rid of field-by-field copyin

From: Al Viro <viro@...iv.linux.org.uk>

[ Upstream commit 1b3bce4d6bf839304a90951b4b25a5863533bf2a ]

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/tty/vt/vt_ioctl.c | 68 ++++++++++++++++-----------------------
 1 file changed, 27 insertions(+), 41 deletions(-)

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index a86bc7afb3b28..a1e5c408c931b 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -850,58 +850,44 @@ int vt_ioctl(struct tty_struct *tty,
 
 	case VT_RESIZEX:
 	{
-		struct vt_consize __user *vtconsize = up;
-		ushort ll,cc,vlin,clin,vcol,ccol;
+		struct vt_consize v;
 		if (!perm)
 			return -EPERM;
-		if (!access_ok(VERIFY_READ, vtconsize,
-				sizeof(struct vt_consize))) {
-			ret = -EFAULT;
-			break;
-		}
+		if (copy_from_user(&v, up, sizeof(struct vt_consize)))
+			return -EFAULT;
 		/* FIXME: Should check the copies properly */
-		__get_user(ll, &vtconsize->v_rows);
-		__get_user(cc, &vtconsize->v_cols);
-		__get_user(vlin, &vtconsize->v_vlin);
-		__get_user(clin, &vtconsize->v_clin);
-		__get_user(vcol, &vtconsize->v_vcol);
-		__get_user(ccol, &vtconsize->v_ccol);
-		vlin = vlin ? vlin : vc->vc_scan_lines;
-		if (clin) {
-			if (ll) {
-				if (ll != vlin/clin) {
-					/* Parameters don't add up */
-					ret = -EINVAL;
-					break;
-				}
-			} else 
-				ll = vlin/clin;
+		if (!v.v_vlin)
+			v.v_vlin = vc->vc_scan_lines;
+		if (v.v_clin) {
+			int rows = v.v_vlin/v.v_clin;
+			if (v.v_rows != rows) {
+				if (v.v_rows) /* Parameters don't add up */
+					return -EINVAL;
+				v.v_rows = rows;
+			}
 		}
-		if (vcol && ccol) {
-			if (cc) {
-				if (cc != vcol/ccol) {
-					ret = -EINVAL;
-					break;
-				}
-			} else
-				cc = vcol/ccol;
+		if (v.v_vcol && v.v_ccol) {
+			int cols = v.v_vcol/v.v_ccol;
+			if (v.v_cols != cols) {
+				if (v.v_cols)
+					return -EINVAL;
+				v.v_cols = cols;
+			}
 		}
 
-		if (clin > 32) {
-			ret =  -EINVAL;
-			break;
-		}
-		    
+		if (v.v_clin > 32)
+			return -EINVAL;
+
 		for (i = 0; i < MAX_NR_CONSOLES; i++) {
 			if (!vc_cons[i].d)
 				continue;
 			console_lock();
-			if (vlin)
-				vc_cons[i].d->vc_scan_lines = vlin;
-			if (clin)
-				vc_cons[i].d->vc_font.height = clin;
+			if (v.v_vlin)
+				vc_cons[i].d->vc_scan_lines = v.v_vlin;
+			if (v.v_clin)
+				vc_cons[i].d->vc_font.height = v.v_clin;
 			vc_cons[i].d->vc_resize_user = 1;
-			vc_resize(vc_cons[i].d, cc, ll);
+			vc_resize(vc_cons[i].d, v.v_cols, v.v_rows);
 			console_unlock();
 		}
 		break;
-- 
2.20.1