Re: [PATCH] net/sched: sch_qfq: Fix null-deref in agg_dequeue

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Jul 02, 2025 at 12:18:18AM -0700, Xiang Mei wrote:
> To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c)
> when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return
> value before using it, similar to the existing approach in sch_hfsc.c.
> 
> To avoid code duplication, the following changes are made:
> 
> 1. Moved qdisc_warn_nonwc to include/net/sch_generic.h and removed
> its EXPORT_SYMBOL declaration, since all users include the header.
> 
> 2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to
> include/net/sch_generic.h so that sch_qfq can reuse it.
> 
> 3. Applied qdisc_peek_len in agg_dequeue to avoid crashing.
> 
> Signed-off-by: Xiang Mei <xmei5@asu.edu>
> ---
>  include/net/sch_generic.h | 24 ++++++++++++++++++++++++
>  net/sched/sch_api.c       | 10 ----------
>  net/sched/sch_hfsc.c      | 16 ----------------
>  net/sched/sch_qfq.c       |  2 +-
>  4 files changed, 25 insertions(+), 27 deletions(-)
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
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