From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.214.175 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793009153; b=QPK1DK37nCblVHKLZ0Ce3VVCT9X5jA6UGitHNZs7LXTpDo3weh1BobUYVSkbA9LOI5l5 8iETGjozbVThP4XzmvTsTRSUDUoYXzGduoJ3XMbwPp2Swrj8Z/L52yvBJ443wV1GvTr5F AEkxPtHCuUGLGdtHoitq0n262eyrX/t1SytiApFA7cFdlXv+q47c8V4GbisJEdyRqn/pB YO8dHCCTF6ehYYRBICgZBLDhpfdXkRb9Kr4MtW7uZc9vwZ5oV+g5ufBtM6kOGvQ7RD3zp NESuZXkn0zTUxHQAMMUv7fJNUejJSMqJekR2awYyX5wAmBn6XpX0hMZnr8ouZOijd+Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793009153; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Gm-Message-State:X-Gm-Gg:X-Received:Received:From:To:Cc:Subject: Date:Message-ID:X-Mailer:MIME-Version:Content-Transfer-Encoding; bh=Gm/vkZ/TPKkcuQ8IJYMQfAw8BN32mGEm+OiB1P+AHxg=; b=XyAwOPcd55WNn7wfIgKyyNEQwQZ7s2btZ5lGKtuIOKLB4qlAWKEoEmjGuTi0shG6S/Bl j4W7fJ7Lmi6crGv7AN0zy2AWKsSYH5dcK2Iy9fp57bWk0+rFIh44fgnciIgXgBfBaTIRi v1HiNnuEJghPuPT9x0LLiGggqP+UMomOxTWanY0c/nBHTBCD2ct2MxH06BHyoUPkQkrVZ oxX0muJC231HlgKcR7m4xMOslzmWZVAvhe5IkYOFi8+D66rnMKGqMfdfCrYUwPQX4LcUv A0rYjagB9cYcYX5+fOnVed1gR+KXwJuxzRX51GekCyDXFaR+LQc+tV1IiizqmN9DfqQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=oGltNea8; arc=none smtp.remote-ip=209.85.214.175 Received: from mail-pl1-f175.google.com (mail-pl1-f175.google.com [209.85.214.175]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CD74F606A33E for ; Mon, 26 Oct 2026 10:05:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org CD74F606A33E Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=oGltNea8 Received: by mail-pl1-f175.google.com with SMTP id d9443c01a7336-2e608cd460eso17496105ad.3 for ; Mon, 26 Oct 2026 03:05:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1793009152; x=1793613952; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=Gm/vkZ/TPKkcuQ8IJYMQfAw8BN32mGEm+OiB1P+AHxg=; b=oGltNea8Icpks0AKShXXj02HZ9E927nFFfMwJpBRbJKt458wbXwSFBWWA3+ghZw51E vAqvMNSIm+aJR5miw5r+rD46K2/d/dLNahVUsw5BatL/CY6yKy/VK3/v7lvIwdYP6Ncv 2HT6AupXt9ynFYBu9eLulOEkm+OgX1tOE3r2peQ4oxqubYTuOFjWpxRbcTe44ySoxVsq Dwa7R+baX9Qj2Gz4dQnI4dqy/BQ392ZtfmWA5pGM61MCheekfpKiVQ4VG4rdGApp3+xr 1uJESliw7mMLBpst5JWXhkqgGWWWl6wZVtxYFgUGC5oYVY7oMOEffn8aEX/I8WlA+F7W /vuQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793009152; x=1793613952; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=Gm/vkZ/TPKkcuQ8IJYMQfAw8BN32mGEm+OiB1P+AHxg=; b=YVq/pYOKUFNXYMMjm8JKr82SLa4I8hM/ikjpek8OkU/aSMHvef/egSIz7itKF+X0dr SyAN+XerEh34JcQtWUV5ITgh7Xlmgcc/on8UFtb9Rw1tUsw8xARB9LlZK0SNra8GZ+mX bsxeEIfy2cQlLUxQeUA/8V34c5m0rdnuZBHU8W9LACJzDbaTXxd+BRDsW6gk/DJfSGOE 9XNCwNgz5bxbERtyo6l2nSVIwPleX0UHDUZsngTP6F5q+PdZ69nrxOLbkbJ4M9UpkYlY geWMkggT8ZmBuKCK1jL9oFuq57adcQgxS9QEXZf5kaXrA7HfH4JCWpCherZ7Kbz+1Ffb AMHw== X-Gm-Message-State: AFq9FYLlNimZrq9u8Jzzk4LFPyxqoYd4emhA73CdW3LvB/ZLnQCKoq6t GiF7PrR8qrKyK0YAM6LMjJDKVXfcG70opUQVU5+eFUm0XH6Ut58VaKuL X-Gm-Gg: AYBFou1RegHkCTA6g02UT+1YelUJ60ssHhs7T0RMaG+Q/ZrMWfgfi/1CpoI27HQeINa QW9i3jas6N12eSBeRPgkiBzqW72H/jq1fQwOMR6NagNVkbzEcv43df7GjuaHt17zd5Pn71/RFUO uvwCm4b0ICSNNYphbmY4fwsvEN7qu9ZcncVh4T8LnWfIzqSxA4AqXTo97iHNASjF3ofcBkaM+d9 duDhYZ2yzWqwV034y+pu7mBUvy/3v/pzs+zT4El/D2dh9OaJGmrXk4XVNnmEzlJAQo3Nsb99AX4 X9Ix/IBOCM5VzArivoOSbi/eHCiydaqFtH6J9o+ekHI8TKNG7lxLElEN/di9vEoQeCe4aL0r1OY Y12QCw44W1UWnUhZ/p7PeshY/j7FQD1ulCa26vesIw4iq+bMXkyLgiAm2tp5+DfKK9m8CV3b+uw HQySG9lcPJVG7Rwvgh8m4+vxsWL7rLLRODFLjq9wzA8nFIyarh8BBKmPPlqbRzpBB83lYMPVjM3 8/okfngGqW6WU5EOew6pfhRn6LSwkZbcr+D2OZimEoNTz56XWwvIIDuyoCqYG5/lAZz2234Pgu3 b/7F2NZUAqh2U14/t4M+5SWec52o2Q+1HdlqqwAuHv+VcZEze4I++bFQPZgTaGJgG1wgRXwTtgX DdLwrpFiwI965NOKb5eRgt/BgVK7v X-Received: by 2002:a17:90b:224b:b0:3ac:d19e:85f1 with SMTP id 98e67ed59e1d1-3adeafd6bc7mr4882037a91.53.1793009152103; Mon, 26 Oct 2026 03:05:52 -0700 (PDT) Received: from EAIT-H54D9Q2FJQ.eait.uq.edu.au ([130.102.10.17]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3adeb83b35esm4837686a91.0.2026.10.26.03.05.45 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 26 Oct 2026 03:05:51 -0700 (PDT) From: Yu Zhang To: Richard Cochran Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Yu Zhang Subject: [PATCH] ptp: fix use-after-free in extts_fifo_show() reading tsevqs unlocked Date: Mon, 26 Oct 2026 20:05:35 +1000 Message-ID: <20261026100535.68114-1-yuz08559@gmail.com> X-Mailer: git-send-email 2.55.0 X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit extts_fifo_show() walks ptp->tsevqs with list_count_nodes() and then list_first_entry() without holding ptp->tsevqs_lock, the spinlock that "protects tsevqs from concurrent access". Every other accessor of the list honours it: ptp_open() (list_add_tail), ptp_release() (list_del followed by kfree of the per-fd queue), ptp_clock_release() and ptp_clock_event() all take tsevqs_lock. extts_fifo_show() is the only one that does not. A per-fd timestamp queue is appended to tsevqs on open("/dev/ptpN") and removed and freed on close(), both under tsevqs_lock: scoped_guard(spinlock_irq, &ptp->tsevqs_lock) list_del(&queue->qlist); bitmap_free(queue->mask); kfree(queue); So a read of /sys/class/ptp/ptpN/fifo running concurrently with a close() of a /dev/ptpN fd can have list_count_nodes() walk into the queue that close() is removing and freeing, dereferencing freed memory (use-after-free) or a poisoned list pointer. Take tsevqs_lock around the list walk. The fifo only ever draws from the first queue, which is the registration-time queue created in ptp_clock_register() and freed only in ptp_clock_release(); that cannot run while the sysfs attribute is being read, so the dequeue from queue->buf under queue->lock may stay outside tsevqs_lock and the lock order is unchanged. Fixes: d26ab5a35ad9 ("ptp: Replace timestamp event queue with linked list") Cc: stable@vger.kernel.org Signed-off-by: Yu Zhang --- drivers/ptp/ptp_sysfs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c index dc398c6..7d09256 100644 --- a/drivers/ptp/ptp_sysfs.c +++ b/drivers/ptp/ptp_sysfs.c @@ -80,13 +80,17 @@ static ssize_t extts_fifo_show(struct device *dev, size_t qcnt; int cnt = 0; + spin_lock_irqsave(&ptp->tsevqs_lock, flags); cnt = list_count_nodes(&ptp->tsevqs); - if (cnt <= 0) + if (cnt <= 0) { + spin_unlock_irqrestore(&ptp->tsevqs_lock, flags); goto out; + } /* The sysfs fifo will always draw from the fist queue */ queue = list_first_entry(&ptp->tsevqs, struct timestamp_event_queue, qlist); + spin_unlock_irqrestore(&ptp->tsevqs_lock, flags); memset(&event, 0, sizeof(event)); spin_lock_irqsave(&queue->lock, flags); -- 2.43.0