From: Bryam Vargas <hexlabsecurity@proton.me>
To: Jakub Kicinski <kuba@kernel.org>
Cc: "D . Wythe" <alibuda@linux.alibaba.com>,
Dust Li <dust.li@linux.alibaba.com>,
Sidraya Jayagond <sidraya@linux.ibm.com>,
Wenjia Zhang <wenjia@linux.ibm.com>,
Mahanta Jambigi <mjambigi@linux.ibm.com>,
Tony Lu <tonylu@linux.alibaba.com>,
Wen Gu <guwen@linux.alibaba.com>,
"David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Stefan Raspl <raspl@linux.ibm.com>,
Ursula Braun <ubraun@linux.ibm.com>,
linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net/smc: bound the peer producer cursor on SMC-D and SMC-R CDC receive
Date: Sun, 14 Jun 2026 08:32:53 +0000 [thread overview]
Message-ID: <20260614083242.79320-1-hexlabsecurity@proton.me> (raw)
In-Reply-To: <20260614003111.383195-1-kuba@kernel.org>
On Sat, 13 Jun 2026 17:31:11 -0700, Jakub Kicinski wrote:
> Is this clamp safe against a concurrent smc_rx_recvmsg() on another CPU?
Confirmed -- the tasklet read-then-set is racy: a recvmsg()/sendmsg() on
another CPU reads the inflated value in the window between the
atomic_add() and the clamp (recvmsg() runs under lock_sock(), which
leaves the slock free, so it is not serialized against the
bh_lock_sock() CDC tasklet). Reworked as a v3 series:
https://lore.kernel.org/netdev/20260614-b4-disp-edd64be9-v3-0-551fa514257e@proton.me/
The bound now lives at the consumer (smc_rx_recvmsg() / smc_tx_sendmsg()),
where it is race-free; it also rejects a sign-overflowed (negative)
accumulator (per the sashiko-bot review on the sndbuf_space patch); and
the producer-cursor clamp is applied to the producer cursor only, so the
consumer cursor stays bounded by peer_rmbe_size, not rmb_desc->len. The
sndbuf_space fix is folded in as patch 3/3.
Thanks for the review.
Bryam
prev parent reply other threads:[~2026-06-14 8:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-10 8:48 [PATCH] net/smc: bound the peer producer cursor on SMC-D and SMC-R CDC receive Bryam Vargas
2026-06-11 8:48 ` sashiko-bot
2026-06-14 0:31 ` Jakub Kicinski
2026-06-14 8:32 ` Bryam Vargas [this message]
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