From cc4916adf2c3f310008e78adb40a94238724d606 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Tue, 29 Mar 2016 19:59:44 +0000
Subject: [PATCH] Do not access buffer if bread(9) or cluster_read(9) failed. 
 On error, the functions free the buffer and set the pointer to NULL.  Also
 remove useless call to brelse(9) on the error path.

PR:	208275
Submitted by:	Fabian Keil <fk@fabiankeil.de>
MFC after:	2 weeks
---
 sys/fs/cd9660/cd9660_vnops.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/sys/fs/cd9660/cd9660_vnops.c b/sys/fs/cd9660/cd9660_vnops.c
index 47d4f757713e..cab8db7e39dc 100644
--- a/sys/fs/cd9660/cd9660_vnops.c
+++ b/sys/fs/cd9660/cd9660_vnops.c
@@ -341,11 +341,9 @@ cd9660_read(ap)
 			} else
 				error = bread(vp, lbn, size, NOCRED, &bp);
 		}
-		n = MIN(n, size - bp->b_resid);
-		if (error) {
-			brelse(bp);
+		if (error != 0)
 			return (error);
-		}
+		n = MIN(n, size - bp->b_resid);
 
 		error = uiomove(bp->b_data + on, (int)n, uio);
 		brelse(bp);