Patch "NFS: Fix inode corruption in nfs_prime_dcache()" has been added to the 4.8-stable tree

Patch "NFS: Fix inode corruption in nfs_prime_dcache()" has been added to the 4.8-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    NFS: Fix inode corruption in nfs_prime_dcache()

to the 4.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfs-fix-inode-corruption-in-nfs_prime_dcache.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 7dc72d5f7a0ec97a53e126c46e2cbd2560757955 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Thu, 22 Sep 2016 13:38:52 -0400
Subject: NFS: Fix inode corruption in nfs_prime_dcache()

From: Trond Myklebust <trond.myklebust@primarydata.com>

commit 7dc72d5f7a0ec97a53e126c46e2cbd2560757955 upstream.

Due to inode number reuse in filesystems, we can end up corrupting the
inode on our client if we apply the file attributes without ensuring that
the filehandle matches.
Typical symptoms include spurious "mode changed" reports in the syslog.

We still do want to ensure that we don't invalidate the dentry if the
inode number matches, but we don't have a filehandle.

Fixes: fa9233699cc1 ("NFS: Don't require a filehandle to refresh...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfs/dir.c |   16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -435,11 +435,11 @@ int nfs_same_file(struct dentry *dentry,
 		return 0;
 
 	nfsi = NFS_I(inode);
-	if (entry->fattr->fileid == nfsi->fileid)
-		return 1;
-	if (nfs_compare_fh(entry->fh, &nfsi->fh) == 0)
-		return 1;
-	return 0;
+	if (entry->fattr->fileid != nfsi->fileid)
+		return 0;
+	if (entry->fh->size && nfs_compare_fh(entry->fh, &nfsi->fh) != 0)
+		return 0;
+	return 1;
 }
 
 static
@@ -517,6 +517,8 @@ again:
 					&entry->fattr->fsid))
 			goto out;
 		if (nfs_same_file(dentry, entry)) {
+			if (!entry->fh->size)
+				goto out;
 			nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
 			status = nfs_refresh_inode(d_inode(dentry), entry->fattr);
 			if (!status)
@@ -529,6 +531,10 @@ again:
 			goto again;
 		}
 	}
+	if (!entry->fh->size) {
+		d_lookup_done(dentry);
+		goto out;
+	}
 
 	inode = nfs_fhget(dentry->d_sb, entry->fh, entry->fattr, entry->label);
 	alias = d_splice_alias(inode, dentry);


Patches currently in stable-queue which might be from trond.myklebust@primarydata.com are

queue-4.8/nfsv4-don-t-report-revoked-delegations-as-valid-in-nfs_have_delegation.patch
queue-4.8/nfs-fix-inode-corruption-in-nfs_prime_dcache.patch
queue-4.8/nfsv4.2-fix-a-reference-leak-in-nfs42_proc_layoutstats_generic.patch
queue-4.8/nfsv4-open-state-recovery-must-account-for-file-permission-changes.patch
queue-4.8/nfsv4-nfs4_copy_delegation_stateid-must-fail-if-the-delegation-is-invalid.patch