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[PATCH 03/30] check for null vfsmount in dentry_open()

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From: Dave Hansen <haveblue@...>
To: <linux-kernel@...>
Cc: <hch@...>, <miklos@...>, <akpm@...>, Dave Hansen <haveblue@...>
Subject: [PATCH 03/30] check for null vfsmount in dentry_open()
Date: Friday, February 15, 2008 - 6:37 pm

Make sure no-one calls dentry_open with a NULL vfsmount argument and crap
out with a stacktrace otherwise.  A NULL file->f_vfsmnt has always been
problematic, but with the per-mount r/o tracking we can't accept anymore
at all.

Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

 linux-2.6.git-dave/fs/open.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff -puN fs/open.c~check-for-NULL-vfsmount-in-dentry-open fs/open.c
--- linux-2.6.git/fs/open.c~check-for-NULL-vfsmount-in-dentry-open	2008-02-15 13:25:42.000000000 -0800
+++ linux-2.6.git-dave/fs/open.c	2008-02-15 13:25:42.000000000 -0800
@@ -903,6 +903,18 @@ struct file *dentry_open(struct dentry *
 	int error;
 	struct file *f;
 
+	/*
+	 * We must always pass in a valid mount pointer.   Historically
+	 * callers got away with not passing it, but we must enforce this at
+	 * the earliest possible point now to avoid strange problems deep in the
+	 * filesystem stack.
+	 */
+	if (!mnt) {
+		printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
+		dump_stack();
+		return ERR_PTR(-EINVAL);
+	}
+
 	error = -ENFILE;
 	f = get_empty_filp();
 	if (f == NULL) {
_
--
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Messages in current thread:
[PATCH 00/30] Read-only bind mounts (-mm resend), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH] r/o bind mounts: stub functions, Dave Hansen, (Fri Feb 15, 9:32 pm)
[PATCH 30/30] r/o bind mounts: debugging for missed calls, Dave Hansen, (Fri Feb 15, 6:38 pm)
[PATCH 29/30] r/o bind mounts: honor mount writer counts at ..., Dave Hansen, (Fri Feb 15, 6:38 pm)
[PATCH 28/30] r/o bind mounts: track numbers of writers to m..., Dave Hansen, (Fri Feb 15, 6:37 pm)
Re: [PATCH 28/30] r/o bind mounts: track numbers of writers ..., Miklos Szeredi, (Mon Feb 18, 12:10 pm)
Re: [PATCH 28/30] r/o bind mounts: track numbers of writers ..., Dave Hansen, (Wed Feb 20, 5:12 pm)
[PATCH 27/30] r/o bind mounts: get callers of vfs_mknod/crea..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 26/30] r/o bind mounts: check mnt instead of superblo..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 22/30] r/o bind mounts: elevate write count for chmod..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 25/30] r/o bind mounts: make access() use new r/o hel..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 24/30] r/o bind mounts: elevate count for xfs timesta..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 23/30] r/o bind mounts: write counts for truncate(), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 21/30] r/o bind mounts: get write access for vfs_rena..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 20/30] r/o bind mounts: elevate write count for open()s, Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 19/30] r/o bind mounts: elevate write count for ioctl..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 18/30] r/o bind mounts: write counts for link/symlink, Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 17/30] r/o bind mounts: write count for file_update_t..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 06/30] merge open_namei() and do_filp_open(), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 16/30] r/o bind mounts: elevate write count for do_ut..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 15/30] r/o bind mounts: write counts for time functions, Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 14/30] r/o bind mounts: elevate write count for ncp_i..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 13/30] r/o bind mounts: elevate write count for xattr..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 12/30] r/o bind mounts: elevate mnt_writers for unlin..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 11/30] r/o bind mounts: elevate write count for calle..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 10/30] r/o bind mounts: elevate write count for vfs_r..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 08/30] r/o bind mounts: create helper to drop file wr..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 05/30] do namei_flags calculation inside open_namei(), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 03/30] check for null vfsmount in dentry_open(), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 07/30] r/o bind mounts: stub functions, Dave Hansen, (Fri Feb 15, 6:37 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Theodore Tso, (Fri Feb 15, 8:32 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Dave Hansen, (Fri Feb 15, 8:49 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Theodore Tso, (Fri Feb 15, 9:00 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Andrew Morton, (Fri Feb 15, 9:11 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Christoph Hellwig, (Sat Feb 16, 2:31 am)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Dave Hansen, (Wed Feb 20, 6:25 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Christoph Hellwig, (Wed Feb 20, 6:58 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Andrew Morton, (Sat Feb 16, 2:46 am)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Dave Hansen, (Mon Feb 18, 3:06 am)
[PATCH 09/30] r/o bind mounts: drop write during emergency r..., Dave Hansen, (Fri Feb 15, 6:37 pm)
Re: [PATCH 09/30] r/o bind mounts: drop write during emergen..., Miklos Szeredi, (Mon Feb 18, 12:29 pm)
Re: [PATCH 09/30] r/o bind mounts: drop write during emergen..., Al Viro, (Sat Feb 23, 9:38 am)
[PATCH 01/30] reiserfs: eliminate private use of struct file..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 04/30] fix up new filp allocators, Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 02/30] hppfs pass vfsmount to dentry_open(), Dave Hansen, (Fri Feb 15, 6:37 pm)