From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Wahren Subject: [PATCH RFC 1/3] i2c: bcm2835: Avoid possible NULL ptr dereference Date: Thu, 16 Feb 2017 21:20:45 +0000 Message-ID: <1487280047-29608-2-git-send-email-stefan.wahren@i2se.com> References: <1487280047-29608-1-git-send-email-stefan.wahren@i2se.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <1487280047-29608-1-git-send-email-stefan.wahren@i2se.com> Sender: linux-i2c-owner@vger.kernel.org To: Eric Anholt , Wolfram Sang , Peter Robinson Cc: Martin Sperl , =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= , Catalin Marinas , Will Deacon , Rob Herring , Frank Rowand , Florian Fainelli , linux-rpi-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-i2c@vger.kernel.org, Stefan Wahren List-Id: devicetree@vger.kernel.org Since commit e2474541032d ("bcm2835: Fix hang for writing messages larger than 16 bytes") the interrupt handler is prone to a possible NULL pointer dereference. This could happen if an interrupt fires before curr_msg is set by bcm2835_i2c_xfer_msg() and randomly occurs on the RPi 3. Even this is an unexpected behavior the driver must handle that with an error instead of a crash. CC: Noralf Trønnes CC: Martin Sperl Reported-by: Peter Robinson Fixes: e2474541032d ("bcm2835: Fix hang for writing messages larger than 16 bytes") Signed-off-by: Stefan Wahren --- drivers/i2c/busses/i2c-bcm2835.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c index c3436f6..10e39c8 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -195,7 +195,9 @@ static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) } if (val & BCM2835_I2C_S_DONE) { - if (i2c_dev->curr_msg->flags & I2C_M_RD) { + if (!i2c_dev->curr_msg) { + dev_err(i2c_dev->dev, "Got unexpected interrupt (from firmware?)\n"); + } else if (i2c_dev->curr_msg->flags & I2C_M_RD) { bcm2835_drain_rxfifo(i2c_dev); val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); } -- 1.7.9.5