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    SubjectRe: [PATCH] autofs4: Do not potentially dereference NULL pointer returned by fget() in autofs_dev_ioctl_setpipefd()
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    On Mon, 2011-01-24 at 21:03 +0100, Jesper Juhl wrote:
    > On Mon, 24 Jan 2011, Jesper Juhl wrote:
    >
    > > Hi Ian,
    > >
    > > On Sat, 18 Dec 2010, Jesper Juhl wrote:
    > >
    > > > Hi,
    > > >
    > > > In fs/autofs4/dev-ioctl.c::autofs_dev_ioctl_setpipefd() we call fget(),
    > > > which may return NULL, but we do not explicitly test for that NULL return
    > > > so we may end up dereferencing a NULL pointer - bad.
    > > >
    > > > When I originally submitted this patch I had chosen EBUSY as the return
    > > > value to use if this happens. Ian Kent was kind enough to explain why that
    > > > would most likely be wrong and why EBADF should most likely be used
    > > > instead. This version of the patch uses EBADF.
    > > >
    > > >
    > > > Signed-off-by: Jesper Juhl <jj@chaosbits.net>
    > > > ---
    > > > dev-ioctl.c | 4 ++++
    > > > 1 file changed, 4 insertions(+)
    > > >
    > > > diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
    > > > index eff9a41..a650d7e 100644
    > > > --- a/fs/autofs4/dev-ioctl.c
    > > > +++ b/fs/autofs4/dev-ioctl.c
    > > > @@ -372,6 +372,10 @@ static int autofs_dev_ioctl_setpipefd(struct file *fp,
    > > > return -EBUSY;
    > > > } else {
    > > > struct file *pipe = fget(pipefd);
    > > > + if (!pipe) {
    > > > + err = -EBADF;
    > > > + goto out;
    > > > + }
    > > > if (!pipe->f_op || !pipe->f_op->write) {
    > > > err = -EPIPE;
    > > > fput(pipe);
    > > >
    > >
    > > It's been more than a month now since I submitted this updated patch
    > > adressing your feedback, but I've not seen any feedback on it.
    > > Is it OK? Will you merge it?
    > >
    > Ok, I need to learn to search my mailbox better. I just saw that you did
    > indeed send a reply with an Acked-by: on december 28.
    >
    > Doesn't change the fact that I still need to find someone to actually
    > merge it...
    >

    Often patches like this get merged whether I ack them or not.

    Right now I'm struggling with the 2.6.38-rc changes since the merge of
    vfs-scale together with the vfs-automount patches caused some breakage.

    I will post it along with any other patches I end up with if it doesn't
    get picked up beforehand.

    Ian



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