From: George Kennedy <george.kennedy@oracle.com>
Date: Mon, 27 Feb 2023 20:21:41 +0000 (-0500)
Subject: vc_screen: modify vcs_size() handling in vcs_read()
X-Git-Tag: v4.19.276~26
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=61a96ad27addecaba100213c7089bf2ebd20c6e4;p=thirdparty%2Fkernel%2Fstable.git

vc_screen: modify vcs_size() handling in vcs_read()

[ Upstream commit 46d733d0efc79bc8430d63b57ab88011806d5180 ]

Restore the vcs_size() handling in vcs_read() to what
it had been in previous version.

Fixes: 226fae124b2d ("vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF")
Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index 5b5e800ab1549..28bc9c70de3ec 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -278,10 +278,8 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 		 */
 		size = vcs_size(inode);
 		if (size < 0) {
-			if (read)
-				break;
 			ret = size;
-			goto unlock_out;
+			break;
 		}
 		if (pos >= size)
 			break;