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From:   Johan Hovold <johan+linaro@kernel.org>
To:     Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Amol Maheshwari <amahesh@qti.qualcomm.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Bjorn Andersson <andersson@kernel.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Johan Hovold <johan+linaro@kernel.org>, stable@vger.kernel.org
Subject: [PATCH 1/3] misc: fastrpc: fix memory corruption on probe
Date:   Mon, 29 Aug 2022 10:05:29 +0200
Message-Id: <20220829080531.29681-2-johan+linaro@kernel.org>
In-Reply-To: <20220829080531.29681-1-johan+linaro@kernel.org>
References: <20220829080531.29681-1-johan+linaro@kernel.org>
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Add the missing sanity check on the probed-session count to avoid
corrupting memory beyond the fixed-size slab-allocated session array
when there are more than FASTRPC_MAX_SESSIONS sessions defined in the
devicetree.

Fixes: f6f9279f2bf0 ("misc: fastrpc: Add Qualcomm fastrpc basic driver model")
Cc: stable@vger.kernel.org      # 5.1
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/misc/fastrpc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 93ebd174d848..88091778c1b8 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -1943,6 +1943,11 @@ static int fastrpc_cb_probe(struct platform_device *pdev)
 	of_property_read_u32(dev->of_node, "qcom,nsessions", &sessions);
 
 	spin_lock_irqsave(&cctx->lock, flags);
+	if (cctx->sesscount >= FASTRPC_MAX_SESSIONS) {
+		dev_err(&pdev->dev, "too many sessions\n");
+		spin_unlock_irqrestore(&cctx->lock, flags);
+		return -ENOSPC;
+	}
 	sess = &cctx->session[cctx->sesscount];
 	sess->used = false;
 	sess->valid = true;
-- 
2.35.1