On Thu, Jan 03, 2019 at 09:49:27PM -0500, Steven Rostedt wrote: > On Thu, 3 Jan 2019 16:42:03 -0800 > John Sperbeck <jsperbeck@xxxxxxxxxx> wrote: > > > If an smbus transfer fails, there's no guarantee that the output > > buffer was written. So, avoid copying from the output buffer when > > tracing after an error. This was 'mostly harmless', but would trip > > up kasan checking if left-over cruft in byte 0 is a large length, > > causing us to read from unwritten memory. > > > > Signed-off-by: John Sperbeck <jsperbeck@xxxxxxxxxx> > > --- > > drivers/i2c/i2c-core-smbus.c | 2 +- > > include/trace/events/smbus.h | 10 +++++----- > > 2 files changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c > > index 9cd66cabb84f..132119112596 100644 > > --- a/drivers/i2c/i2c-core-smbus.c > > +++ b/drivers/i2c/i2c-core-smbus.c > > @@ -585,7 +585,7 @@ s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, > > trace: > > /* If enabled, the reply tracepoint is conditional on read_write. */ > > trace_smbus_reply(adapter, addr, flags, read_write, > > - command, protocol, data); > > + command, protocol, data, res); > > trace_smbus_result(adapter, addr, flags, read_write, > > command, protocol, res); > > > > diff --git a/include/trace/events/smbus.h b/include/trace/events/smbus.h > > index d2fb6e1d3e10..b6376a7c7e74 100644 > > --- a/include/trace/events/smbus.h > > +++ b/include/trace/events/smbus.h > > @@ -138,8 +138,8 @@ TRACE_EVENT_CONDITION(smbus_reply, > > TP_PROTO(const struct i2c_adapter *adap, > > u16 addr, unsigned short flags, > > char read_write, u8 command, int protocol, > > - const union i2c_smbus_data *data), > > - TP_ARGS(adap, addr, flags, read_write, command, protocol, data), > > + const union i2c_smbus_data *data, int res), > > + TP_ARGS(adap, addr, flags, read_write, command, protocol, data, res), > > TP_CONDITION(read_write == I2C_SMBUS_READ), > > Hmm, instead of tracing nothing, as this is already a "conditional > trace event", why not add to that condition: > > TP_CONDITION(res >= 0 && read_write == I2C_SMBUS_READ), > > Unless you want to still trace some data on failure. John, any comment to this?
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