From 08ae439c95d164e9c0022e0511f4fbb4deffd220 Mon Sep 17 00:00:00 2001 From: Stefan Wahren Date: Thu, 16 Feb 2017 21:20:45 +0000 Subject: [PATCH] i2c: bcm2835: Avoid possible NULL ptr dereference MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit [ Upstream commit ababb08938df7ac245d30a58b95b94ecf8dc04fc ] 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. Reported-by: Peter Robinson Fixes: e2474541032d ("bcm2835: Fix hang for writing messages larger than 16 bytes") Signed-off-by: Stefan Wahren Acked-by: Noralf Trønnes Signed-off-by: Wolfram Sang Signed-off-by: Sasha Levin --- 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 f283b71..7ed0986 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -128,7 +128,9 @@ 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); } -- 2.7.4