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([39.170.101.209]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a79e7c243csm2603661a91.0.2026.10.04.05.06.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Oct 2026 05:06:16 -0700 (PDT) From: Zxyan Zhu To: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, richardcochran@gmail.com, maxime.chevallier@bootlin.com, muhammad.nazim.amirul.nazle.asmade@altera.com, rohan.g.thomas@altera.com, netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Zxyan Zhu , stable@vger.kernel.org Subject: [PATCH net-next v7 2/3] net: stmmac: guard against a zero channel in the aux snapshot handler Date: Sun, 4 Oct 2026 20:05:25 +0800 Message-Id: <20261004120526.2728564-3-zxyan0222@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261004120526.2728564-1-zxyan0222@gmail.com> References: <20261004120526.2728564-1-zxyan0222@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The generic timestamp_interrupt() handler derives the EXTTS channel index with ilog2() applied directly to the PTP_ACR channel mask, with no check for a zero mask. ilog2(0) yields -1, which ends up in event.index as 0xffffffff, and ptp_clock_event() uses that index in test_bit() against a PTP_MAX_CHANNELS bitmap without range validation, reading far past the allocation from hard IRQ context. The zero-mask window is reachable: stmmac_enable() sets STMMAC_FLAG_EXT_SNAPSHOT_EN before it programs PTP_ACR, so an EXTTS interrupt arriving in between passes the flag check while the mask is still clear (snapshots can also linger in the FIFO from a previous enable, as only PTP_ACR_ATSFC clears them). Check the mask before applying the ilog2(). Fixes: 8851346912a1 ("net: stmmac: Assign configured channel value to EXTTS event") Cc: stable@vger.kernel.org Signed-off-by: Zxyan Zhu --- drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c index b9a985fa772c..2a076e228e9a 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c @@ -242,7 +242,10 @@ static void timestamp_interrupt(struct stmmac_priv *priv) GMAC_TIMESTAMP_ATSNS_SHIFT; acr_value = readl(priv->ptpaddr + PTP_ACR); - channel = ilog2(FIELD_GET(PTP_ACR_MASK, acr_value)); + channel = FIELD_GET(PTP_ACR_MASK, acr_value); + if (!channel) + return; + channel = ilog2(channel); for (i = 0; i < num_snapshot; i++) { read_lock_irqsave(&priv->ptp_lock, flags); -- 2.34.1