misc/177328: [patch] libstand fails on ext2fs directories with more than one block

[Eric van Gyzen]

>Number:         177328
>Category:       misc
>Synopsis:       [patch] libstand fails on ext2fs directories with more than one block
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Mar 24 02:50:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Eric van Gyzen
>Release:        8.1-RELEASE
>Organization:
Dell, Inc.
>Environment:
N/A
>Description:
When booting from an ext2fs file system, the loader skips the first 1k of a file if the directory entry for that file isn't in the first 1k of the directory of the root directory.
>How-To-Repeat:
Put several files in the boot directory, then add the kernel, to ensure that the kernel's directory entry isn't in the first block of the directory.
>Fix:
Port this fix from ufs.c (from 2004):

http://svnweb.freebsd.org/base?view=revision&revision=134760

We've been running with the attached patch since August 2011.

Patch attached with submission follows:

diff --git a/src/lib/libstand/ext2fs.c b/src/lib/libstand/ext2fs.c
index 53c4f56..40ce167 100644
--- a/src/lib/libstand/ext2fs.c
+++ b/src/lib/libstand/ext2fs.c
@@ -536,6 +536,17 @@ ext2fs_open(const char *upath, struct open_file *f)
 	 * Found terminal component.
 	 */
 	error = 0;
+
+        // Reset the seek pointer to 0 when a file is successfully opened,
+        // since otherwise the initial seek offset will contain the directory
+        // offset of the filesystem block that contained its directory entry.
+        // This bug was mostly harmless because typically the directory is
+        // less than one filesystem block in size so the offset would be zero.
+        // It did however generally break loading a kernel from the (large)
+        // kernel compile directory.
+        // http://www.freebsd.org/cgi/cvsweb.cgi/src/lib/libstand/ufs.c#rev1.15
+        fp->f_seekp = 0;
+
 out:
 	if (buf)
 		free(buf);
@@ -585,6 +596,16 @@ read_inode(ino_t inumber, struct open_file *f)
 		fp->f_blkno[level] = -1;
 	fp->f_buf_blkno = -1;
 
+        // Reset the seek pointer to 0 when a file is successfully opened,
+        // since otherwise the initial seek offset will contain the directory
+        // offset of the filesystem block that contained its directory entry.
+        // This bug was mostly harmless because typically the directory is
+        // less than one filesystem block in size so the offset would be zero.
+        // It did however generally break loading a kernel from the (large)
+        // kernel compile directory.
+        // http://www.freebsd.org/cgi/cvsweb.cgi/src/lib/libstand/ufs.c#rev1.15
+        fp->f_seekp = 0;
+
 out:
 	free(buf);
 	return (error);	 


>Release-Note:
>Audit-Trail:
>Unformatted: