ACK: [SRU][J/N/O/P][PATCH 0/1] CVE-2025-38083

[Wei-Lin Chang]

On Wed, Jun 25, 2025 at 04:00:02PM -0700, Tim Whisonant wrote:
> SRU Justification:
> 
> [Impact]
> 
> net_sched: prio: fix a race in prio_tune()
> 
> Gerrard Tai reported a race condition in PRIO, whenever SFQ perturb timer
> fires at the wrong time.
> 
> The race is as follows:
> 
> CPU 0                                 CPU 1
> [1]: lock root
> [2]: qdisc_tree_flush_backlog()
> [3]: unlock root
>  |
>  |                                    [5]: lock root
>  |                                    [6]: rehash
>  |                                    [7]: qdisc_tree_reduce_backlog()
>  |
> [4]: qdisc_put()
> 
> This can be abused to underflow a parent's qlen.
> 
> Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog()
> should fix the race, because all packets will be purged from the qdisc
> before releasing the lock.
> 
> [Fix]
> 
> Plucky:   applied Jammy patch
> Oracular: applied Jammy patch
> Noble:    applied Jammy patch
> Jammy:    cherry picked from upstream
> Focal:    patch sent to ESM ML
> Bionic:   not affected
> Xenial:   not affected
> Trusty:   not affected
> 
> [Test Plan]
> 
> Compile and boot tested.
> 
> [Where problems could occur]
> 
> The change affects the Simple 3-band priority (network) scheduler.
> Issues might manifset as packet drops or other unexpected behavior
> in the networking stack.
> 
> Eric Dumazet (1):
>   net_sched: prio: fix a race in prio_tune()
> 
>  net/sched/sch_prio.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> -- 
> 2.43.0
> 
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team

Acked-by: Wei-Lin Chang <weilin.chang at canonical.com>