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Subject[patch 07/37] Have ext2 reject file handles with bad inode numbers early.
-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Neil Brown <neilb@suse.de>
This prevents bad inode numbers from triggering errors in
ext2_get_inode.


Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/ext2/super.c | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
--- linux-2.6.17.11.orig/fs/ext2/super.c
+++ linux-2.6.17.11/fs/ext2/super.c
@@ -252,6 +252,46 @@ static struct super_operations ext2_sops
#endif
};

+static struct dentry *ext2_get_dentry(struct super_block *sb, void *vobjp)
+{
+ __u32 *objp = vobjp;
+ unsigned long ino = objp[0];
+ __u32 generation = objp[1];
+ struct inode *inode;
+ struct dentry *result;
+
+ if (ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb))
+ return ERR_PTR(-ESTALE);
+ if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
+ return ERR_PTR(-ESTALE);
+
+ /* iget isn't really right if the inode is currently unallocated!!
+ * ext2_read_inode currently does appropriate checks, but
+ * it might be "neater" to call ext2_get_inode first and check
+ * if the inode is valid.....
+ */
+ inode = iget(sb, ino);
+ if (inode == NULL)
+ return ERR_PTR(-ENOMEM);
+ if (is_bad_inode(inode)
+ || (generation && inode->i_generation != generation)
+ ) {
+ /* we didn't find the right inode.. */
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
+ /* now to find a dentry.
+ * If possible, get a well-connected one
+ */
+ result = d_alloc_anon(inode);
+ if (!result) {
+ iput(inode);
+ return ERR_PTR(-ENOMEM);
+ }
+ return result;
+}
+
+
/* Yes, most of these are left as NULL!!
* A NULL value implies the default, which works with ext2-like file
* systems, but can be improved upon.
@@ -259,6 +299,7 @@ static struct super_operations ext2_sops
*/
static struct export_operations ext2_export_ops = {
.get_parent = ext2_get_parent,
+ .get_dentry = ext2_get_dentry,
};

static unsigned long get_sb_block(void **data)
--
-
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