On Wed Aug 18, 2010 at 10:49:04 +0800, Bian Naimeng wrote:
> >>> /* We can't create new files, or truncate existing ones here */
> >>> openflags &= ~(O_CREAT|O_TRUNC);
> >>> --
> >> Nope. The problem is the recent switch to LOOKUP_EXCL as the authority
> >> for whether or not we're doing an exclusive create.
> >>
> >> Does the following patch work?
> >>
> >
> > Hi Trond, i guess it's not work.
> >
> > As i see, if we want get LOOKUP_EXCL at nd->flags, we must open file with
> > O_CREAT and O_EXCL, "nd->flags & LOOKUP_EXCL" have the same effect with
> > "(openflags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL)", so i think the kernel
> > still crash, right?
I can confirm, it's oopsing.
> What about this one?
This one works.
>
> We we open a positive file just with O_EXCL but no O_CREAT, may cause kernel crash.
>
> Signed-off-by: Bian Naimeng <biannm@xxxxxxxxxxxxxx>
>
> ---
> fs/namei.c | 7 +++----
> fs/nfs/dir.c | 2 +-
> 2 files changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index 17ea76b..6680a38 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -1813,11 +1813,10 @@ reval:
> nd.intent.open.create_mode = mode;
> nd.flags &= ~LOOKUP_PARENT;
> nd.flags |= LOOKUP_OPEN;
> - if (open_flag & O_CREAT) {
> + if (open_flag & O_CREAT)
> nd.flags |= LOOKUP_CREATE;
> - if (open_flag & O_EXCL)
> - nd.flags |= LOOKUP_EXCL;
> - }
> + if (open_flag & O_EXCL)
> + nd.flags |= LOOKUP_EXCL;
> if (open_flag & O_DIRECTORY)
> nd.flags |= LOOKUP_DIRECTORY;
> if (!(open_flag & O_NOFOLLOW))
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 29539ce..bc25da9 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -1100,7 +1100,7 @@ static int nfs_open_revalidate(struct dentry *dentry, struct nameidata *nd)
> goto no_open_dput;
> openflags = nd->intent.open.flags;
> /* We cannot do exclusive creation on a positive dentry */
> - if ((openflags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
> + if (nd->flags & LOOKUP_EXCL)
> goto no_open_dput;
> /* We can't create new files, or truncate existing ones here */
> openflags &= ~(O_CREAT|O_TRUNC);
> --
> 1.7.0
Adam
--
Adam adam@xxxxxxxxxxxxxxxxxxxx
Lackorzynski http://os.inf.tu-dresden.de/~adam/
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