Re: Patch "cifs: Fix flushing, invalidation and file size with copy_file_range()" has been added to the 6.1-stable tree

From: David Howells <dhowells@redhat.com>
Cc: dhowells@redhat.com, "Jitindar Singh, Suraj" <surajjs@amazon.com>,
	"rohiths.msft@gmail.com" <rohiths.msft@gmail.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"stfrench@microsoft.com" <stfrench@microsoft.com>,
	"pc@manguebit.com" <pc@manguebit.com>,
	"jlayton@kernel.org" <jlayton@kernel.org>,
	"nspmangalore@gmail.com" <nspmangalore@gmail.com>,
	"willy@infradead.org" <willy@infradead.org>,
	"stable-commits@vger.kernel.org" <stable-commits@vger.kernel.org>
Subject: Re: Patch "cifs: Fix flushing, invalidation and file size with copy_file_range()" has been added to the 6.1-stable tree
Date: Fri, 12 Jan 2024 14:26:37 +0000	[thread overview]
Message-ID: <2162109.1705069597@warthog.procyon.org.uk> (raw)
In-Reply-To: <2161774.1705069315@warthog.procyon.org.uk>

David Howells <dhowells@redhat.com> wrote:

> Jitindar Singh, Suraj <surajjs@amazon.com> wrote:
> 
> > When testing the v6.1.69 kernel I bisected an issue to the below commit
> > which was added in v6.1.68. When running the xfstests[1] on cifs I
> > observe a null pointer dereference in cifs_flush_folio() because folio
> > is null and dereferenced in size = folio_size(folio).
> 
> Yeah.  __filemap_get_folio() works differently in v6.1.y.  There it returns a
> folio or NULL.  In 6.7 it returns a folio or a negative error code.  The error
> check in cifs_flush_folio() needs to change to something like:
> 
> 	folio = filemap_get_folio(inode->i_mapping, index);
> 	if (!folio)
> 		return -ENOMEM;

Actually, it should return 0, not -ENOMEM.

David