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From: "Cen Zhang (Microsoft)" <blbllhy@gmail.com>
To: sdf.kernel@gmail.com
Cc: AutonomousCodeSecurity@microsoft.com, blbllhy@gmail.com,
	bpf@vger.kernel.org, davem@davemloft.net, edumazet@google.com,
	horms@kernel.org, kuba@kernel.org, kys@microsoft.com,
	linux-kernel@vger.kernel.org, maciej.fijalkowski@intel.com,
	magnus.karlsson@intel.com, netdev@vger.kernel.org,
	pabeni@redhat.com, sdf@fomichev.me,
	tgopinath@linux.microsoft.com
Subject: Re: [PATCH net] xsk: fix NULL pointer dereference in __xsk_rcv()
Date: Fri, 24 Jul 2026 23:00:26 -0400	[thread overview]
Message-ID: <20260725030026.191412-1-blbllhy@gmail.com> (raw)
In-Reply-To: <amPqFHJBnDEQGmOK@devvm7509.cco0.facebook.com>

> ... which means they are "lost"?

You are right. The UMEM frames already consumed from the Fill Ring must
be recycled into free_list when the packet cannot be completed. 

Since the current loop calls __xsk_rcv_zc_safe(), and therefore
xp_release(), after every allocation, they cannot simply be recycled
after a later failure. I will rework v2 as a two-stage transaction:
first allocate and stage all required buffers, recycling all staged
buffers if any allocation fails; then run the error-free
copy/submit/release loop only after the allocation stage succeeds.

Thanks.

      reply	other threads:[~2026-07-25  3:00 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-24 16:47 [PATCH net] xsk: fix NULL pointer dereference in __xsk_rcv() Cen Zhang (Microsoft)
2026-07-24 22:45 ` Stanislav Fomichev
2026-07-25  3:00   ` Cen Zhang (Microsoft) [this message]

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