From: Tristan Madani <tristmd@gmail.com>
To: netdev-bot+sinfo@kernel.org
Cc: David Heidelberg <david@ixit.cz>,
David S. Miller <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
John W. Linville <linville@tuxdriver.com>,
Samuel Ortiz <sameo@linux.intel.com>,
oe-linux-nfc@lists.linux.dev, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Tristan Madani <tristan@talencesecurity.com>
Subject: Re: [PATCH v2 net] nfc: llcp: use disable_work_sync and timer_shutdown_sync in local_cleanup
Date: Thu, 29 Oct 2026 18:07:03 +0000 [thread overview]
Message-ID: <6ae38b48.a6a2e554.2bec60.2370@mx.google.com> (raw)
In-Reply-To: <179329133392.3327.1911358623600296609@kernel.org>
The issue was found by manual code inspection of the NFC LLCP teardown
path in local_cleanup(). cancel_work_sync() does not prevent the work
from being re-queued, and timer_delete_sync() does not prevent the timer
from being re-armed -- both can race with an incoming LLCP frame that
schedules them again after cancellation.
The issue is theoretical (found by code review, not triggered), but the
race window is real: any LLCP frame arriving between the cancel/delete
calls and kfree(local) can re-queue the work or re-arm the timer,
leading to the callback running after the local structure is freed.
prev parent reply other threads:[~2026-10-29 18:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-29 16:24 [PATCH v2 net] nfc: llcp: use disable_work_sync and timer_shutdown_sync in local_cleanup Tristan Madani
2026-10-29 16:28 ` netdev-bot+sinfo
2026-10-29 18:07 ` Tristan Madani [this message]
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