Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1675340

Re: [PATCH] kref: Avoid null pointer dereference after WARN

Show all headers | View raw

On Mon, Jun 26, 2017 at 08:52:15PM -0700, Kees Cook wrote:
> From: Daniel Micay <danielmicay@gmail.com>
> 
> The WARN_ON() checking for a NULL release pointer should be a BUG()
> since continuing with a NULL release pointer will lead to a NULL
> pointer dereference anyway.
> 
> The kref_put() case is extracted from PaX, and Kees Cook noted it should
> be extended to the other two cases.
> 
> Signed-off-by: Daniel Micay <danielmicay@gmail.com>
> [kees: clarify commit log]
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  include/linux/kref.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/kref.h b/include/linux/kref.h
> index f4156f88f557..82a2c225eae3 100644
> --- a/include/linux/kref.h
> +++ b/include/linux/kref.h
> @@ -66,7 +66,7 @@ static inline void kref_get(struct kref *kref)
>   */
>  static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
>  {
> -	WARN_ON(release == NULL);
> +	BUG_ON(release == NULL);

I remember one complaint was that WARN_ON was "huge" and this bloated
the kernel code a lot.  But then that got fixed up.  Is BUG_ON going to
cause the same complaint again?

thanks,

greg k-h

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH] kref: Avoid null pointer dereference after WARN Kees Cook <keescook@chromium.org> - 2017-06-27 06:00 +0200
  Re: [PATCH] kref: Avoid null pointer dereference after WARN Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-27 09:10 +0200
    Re: [PATCH] kref: Avoid null pointer dereference after WARN "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-27 13:10 +0200
      Re: [PATCH] kref: Avoid null pointer dereference after WARN Andi Kleen <ak@linux.intel.com> - 2017-06-27 16:50 +0200
        Re: [PATCH] kref: Avoid null pointer dereference after WARN "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-27 21:20 +0200
          Re: [PATCH] kref: Avoid null pointer dereference after WARN Andi Kleen <ak@linux.intel.com> - 2017-06-27 21:30 +0200
            Re: [PATCH] kref: Avoid null pointer dereference after WARN Michal Hocko <mhocko@kernel.org> - 2017-06-28 13:30 +0200
    Re: [PATCH] kref: Avoid null pointer dereference after WARN Kees Cook <keescook@chromium.org> - 2017-06-27 20:40 +0200
  Re: [PATCH] kref: Avoid null pointer dereference after WARN Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-28 14:00 +0200

csiph-web