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Subject[patch 16/23] ext3: avoid triggering ext3_error on bad NFS file handle
-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Neil Brown <neilb@suse.de>
The inode number out of an NFS file handle gets passed eventually to
ext3_get_inode_block() without any checking. If ext3_get_inode_block()
allows it to trigger an error, then bad filehandles can have unpleasant
effect - ext3_error() will usually cause a forced read-only remount, or a
panic if `errors=panic' was used.

So remove the call to ext3_error there and put a matching check in
ext3/namei.c where inode numbers are read off storage.

[akpm@osdl.org: fix off-by-one error]
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: "Stephen C. Tweedie" <sct@redhat.com>
Cc: Eric Sandeen <esandeen@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/ext3/inode.c | 13 +++++++------
fs/ext3/namei.c | 15 +++++++++++++--
include/linux/ext3_fs.h | 9 +++++++++
3 files changed, 29 insertions(+), 8 deletions(-)
--- linux-2.6.17.7.orig/fs/ext3/inode.c
+++ linux-2.6.17.7/fs/ext3/inode.c
@@ -2402,14 +2402,15 @@ static unsigned long ext3_get_inode_bloc
struct buffer_head *bh;
struct ext3_group_desc * gdp;

-
- if ((ino != EXT3_ROOT_INO && ino != EXT3_JOURNAL_INO &&
- ino != EXT3_RESIZE_INO && ino < EXT3_FIRST_INO(sb)) ||
- ino > le32_to_cpu(EXT3_SB(sb)->s_es->s_inodes_count)) {
- ext3_error(sb, "ext3_get_inode_block",
- "bad inode number: %lu", ino);
+ if (!ext3_valid_inum(sb, ino)) {
+ /*
+ * This error is already checked for in namei.c unless we are
+ * looking at an NFS filehandle, in which case no error
+ * report is needed
+ */
return 0;
}
+
block_group = (ino - 1) / EXT3_INODES_PER_GROUP(sb);
if (block_group >= EXT3_SB(sb)->s_groups_count) {
ext3_error(sb,"ext3_get_inode_block","group >= groups count");
--- linux-2.6.17.7.orig/fs/ext3/namei.c
+++ linux-2.6.17.7/fs/ext3/namei.c
@@ -1000,7 +1000,12 @@ static struct dentry *ext3_lookup(struct
if (bh) {
unsigned long ino = le32_to_cpu(de->inode);
brelse (bh);
- inode = iget(dir->i_sb, ino);
+ if (!ext3_valid_inum(dir->i_sb, ino)) {
+ ext3_error(dir->i_sb, "ext3_lookup",
+ "bad inode number: %lu", ino);
+ inode = NULL;
+ } else
+ inode = iget(dir->i_sb, ino);

if (!inode)
return ERR_PTR(-EACCES);
@@ -1028,7 +1033,13 @@ struct dentry *ext3_get_parent(struct de
return ERR_PTR(-ENOENT);
ino = le32_to_cpu(de->inode);
brelse(bh);
- inode = iget(child->d_inode->i_sb, ino);
+
+ if (!ext3_valid_inum(child->d_inode->i_sb, ino)) {
+ ext3_error(child->d_inode->i_sb, "ext3_get_parent",
+ "bad inode number: %lu", ino);
+ inode = NULL;
+ } else
+ inode = iget(child->d_inode->i_sb, ino);

if (!inode)
return ERR_PTR(-EACCES);
--- linux-2.6.17.7.orig/include/linux/ext3_fs.h
+++ linux-2.6.17.7/include/linux/ext3_fs.h
@@ -495,6 +495,15 @@ static inline struct ext3_inode_info *EX
{
return container_of(inode, struct ext3_inode_info, vfs_inode);
}
+
+static inline int ext3_valid_inum(struct super_block *sb, unsigned long ino)
+{
+ return ino == EXT3_ROOT_INO ||
+ ino == EXT3_JOURNAL_INO ||
+ ino == EXT3_RESIZE_INO ||
+ (ino >= EXT3_FIRST_INO(sb) &&
+ ino <= le32_to_cpu(EXT3_SB(sb)->s_es->s_inodes_count));
+}
#else
/* Assume that user mode programs are passing in an ext3fs superblock, not
* a kernel struct super_block. This will allow us to call the feature-test
--
-
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