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

[Stefan Bader]

On 26.06.25 01:00, 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(-)
> 

Applied to plucky,noble,jammy:linux/master-next. Thanks.

-Stefan
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