diff mbox series

fanotify: avoid possible NULL dereference

Message ID 20230808091849.505809-1-suhui@nfschina.com
State New
Headers
Series fanotify: avoid possible NULL dereference |

Commit Message

Su Hui Aug. 8, 2023, 9:18 a.m. UTC 
  smatch error:
fs/notify/fanotify/fanotify_user.c:462 copy_fid_info_to_user():
we previously assumed 'fh' could be null (see line 421)

Fixes: afc894c784c8 ("fanotify: Store fanotify handles differently")
Signed-off-by: Su Hui <suhui@nfschina.com>
---
 fs/notify/fanotify/fanotify_user.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Amir Goldstein Aug. 10, 2023, 5:58 p.m. UTC | #1 
On Tue, Aug 8, 2023 at 12:19 PM Su Hui <suhui@nfschina.com> wrote:
>
> smatch error:
> fs/notify/fanotify/fanotify_user.c:462 copy_fid_info_to_user():
> we previously assumed 'fh' could be null (see line 421)
>
> Fixes: afc894c784c8 ("fanotify: Store fanotify handles differently")
> Signed-off-by: Su Hui <suhui@nfschina.com>'

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

> ---
>  fs/notify/fanotify/fanotify_user.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index f69c451018e3..5a5487ae2460 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -459,12 +459,13 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
>         if (WARN_ON_ONCE(len < sizeof(handle)))
>                 return -EFAULT;
>
> -       handle.handle_type = fh->type;
>         handle.handle_bytes = fh_len;
>
>         /* Mangle handle_type for bad file_handle */
>         if (!fh_len)
>                 handle.handle_type = FILEID_INVALID;
> +       else
> +               handle.handle_type = fh->type;
>
>         if (copy_to_user(buf, &handle, sizeof(handle)))
>                 return -EFAULT;
> --
> 2.30.2
>
Jan Kara Jan. 2, 2024, 1:47 p.m. UTC | #2 
On Thu 10-08-23 20:58:16, Amir Goldstein wrote:
> On Tue, Aug 8, 2023 at 12:19 PM Su Hui <suhui@nfschina.com> wrote:
> >
> > smatch error:
> > fs/notify/fanotify/fanotify_user.c:462 copy_fid_info_to_user():
> > we previously assumed 'fh' could be null (see line 421)
> >
> > Fixes: afc894c784c8 ("fanotify: Store fanotify handles differently")
> > Signed-off-by: Su Hui <suhui@nfschina.com>'
> 
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>

I'm sorry but this has somehow fallen through the cracks. 

> > diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> > index f69c451018e3..5a5487ae2460 100644
> > --- a/fs/notify/fanotify/fanotify_user.c
> > +++ b/fs/notify/fanotify/fanotify_user.c
> > @@ -459,12 +459,13 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
> >         if (WARN_ON_ONCE(len < sizeof(handle)))
> >                 return -EFAULT;
> >
> > -       handle.handle_type = fh->type;
> >         handle.handle_bytes = fh_len;

Well, if passed 'fh' is NULL, we have problems later in the function
anyway. E.g. in fanotify_fh_buf() a few lines below. So I think this needs
a bit more work that just this small fixup...

								Honza

> >
> >         /* Mangle handle_type for bad file_handle */
> >         if (!fh_len)
> >                 handle.handle_type = FILEID_INVALID;
> > +       else
> > +               handle.handle_type = fh->type;
> >
> >         if (copy_to_user(buf, &handle, sizeof(handle)))
> >                 return -EFAULT;
> > --
> > 2.30.2
> >
diff mbox series

Patch

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index f69c451018e3..5a5487ae2460 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -459,12 +459,13 @@  static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
 	if (WARN_ON_ONCE(len < sizeof(handle)))
 		return -EFAULT;
 
-	handle.handle_type = fh->type;
 	handle.handle_bytes = fh_len;
 
 	/* Mangle handle_type for bad file_handle */
 	if (!fh_len)
 		handle.handle_type = FILEID_INVALID;
+	else
+		handle.handle_type = fh->type;
 
 	if (copy_to_user(buf, &handle, sizeof(handle)))
 		return -EFAULT;