Hi Paul, > Paul Kocialkowski <paul.kocialkow...@bootlin.com> hat am 21. Dezember 2018 um > 13:11 geschrieben: > > > The driver's interrupt handler checks whether a message is currently > being handled with the curr_msg pointer. When it is NULL, the interrupt > is considered to be unexpected. Similarly, the i2c_start_transfer > routine checks for the remaining number of messages to handle in > num_msgs. > > However, these values are never cleared and always keep the message and > number relevant to the latest transfer (which might be done already and > the underlying message memory might have been freed). > > When an unexpected interrupt hits with the DONE bit set, the isr will > then try to access the flags field of the curr_msg structure, leading > to a fatal page fault. > > Fix the issue by systematically clearing curr_msg and num_msgs in the > driver-wide device structure when a transfer is considered complete. > > Signed-off-by: Paul Kocialkowski <paul.kocialkow...@bootlin.com> > --- > drivers/i2c/busses/i2c-bcm2835.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-bcm2835.c > b/drivers/i2c/busses/i2c-bcm2835.c > index 44deae78913e..5486252f5f2f 100644 > --- a/drivers/i2c/busses/i2c-bcm2835.c > +++ b/drivers/i2c/busses/i2c-bcm2835.c > @@ -298,6 +298,9 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, > struct i2c_msg msgs[], > return -ETIMEDOUT; > } > > + i2c_dev->curr_msg = NULL; > + i2c_dev->num_msgs = 0;
AFAIU this would reduce the chance of a use-after-free dramatically but not completely. Btw: Why did you leave of the i2c transfer timeout case? Thanks Stefan > + > if (!i2c_dev->msg_err) > return num; > > -- > 2.20.1 >
