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From: "Pedro F. Giffuni" <pfg@FreeBSD.org>
Date: Thu, 7 Jan 2016 21:43:43 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: svn commit: r293370 - head/sys/fs/ext2fs
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Author: pfg
Date: Thu Jan  7 21:43:43 2016
New Revision: 293370
URL: https://svnweb.freebsd.org/changeset/base/293370

Log:
  ext2fs: reading mmaped file in Ext4 causes panic
  
  Always call brelse(path.ep_bp), fixing reading EXT4 files using mmap().
  
  Patch by Damjan Jovanovic.
  
  PR:		205938
  MFC after:	1 week

Modified:
  head/sys/fs/ext2fs/ext2_bmap.c

Modified: head/sys/fs/ext2fs/ext2_bmap.c
==============================================================================
--- head/sys/fs/ext2fs/ext2_bmap.c	Thu Jan  7 21:16:44 2016	(r293369)
+++ head/sys/fs/ext2fs/ext2_bmap.c	Thu Jan  7 21:43:43 2016	(r293370)
@@ -96,6 +96,7 @@ ext4_bmapext(struct vnode *vp, int32_t b
 	struct ext4_extent *ep;
 	struct ext4_extent_path path = { .ep_bp = NULL };
 	daddr_t lbn;
+	int ret = 0;
 
 	ip = VTOI(vp);
 	fs = ip->i_e2fs;
@@ -113,15 +114,21 @@ ext4_bmapext(struct vnode *vp, int32_t b
 	ext4_ext_find_extent(fs, ip, lbn, &path);
 	ep = path.ep_ext;
 	if (ep == NULL)
-		return (EIO);
+		ret = EIO;
+	else {
+		*bnp = fsbtodb(fs, lbn - ep->e_blk +
+		    (ep->e_start_lo | (daddr_t)ep->e_start_hi << 32));
 
-	*bnp = fsbtodb(fs, lbn - ep->e_blk +
-	    (ep->e_start_lo | (daddr_t)ep->e_start_hi << 32));
+		if (*bnp == 0)
+			*bnp = -1;
+	}
 
-	if (*bnp == 0)
-		*bnp = -1;
+	if (path.ep_bp != NULL) {
+		brelse(path.ep_bp);
+		path.ep_bp = NULL;
+	}
 
-	return (0);
+	return (ret);
 }
 
 /*