Messages in this thread | | | From | Måns Rullgård <> | Subject | Re: [PATCH] i2c: core: check returned size of emulated smbus block read | Date | Fri, 26 Jun 2020 14:33:54 +0100 |
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Wolfram Sang <wsa@the-dreams.de> writes:
> On Sat, Jun 13, 2020 at 11:41:09AM +0100, Mans Rullgard wrote: >> If the i2c bus driver ignores the I2C_M_RECV_LEN flag (as some of >> them do), it is possible for an I2C_SMBUS_BLOCK_DATA read issued > > Out of interest, which driver did you use?
I saw it with the mv64xxx (Allwinner) and omap (Beaglebone) drivers. From a quick look, it seems like quite a few others have the same problem.
>> on some random device to return an arbitrary value in the first >> byte (and nothing else). When this happens, i2c_smbus_xfer_emulated() >> will happily write past the end of the supplied data buffer, thus >> causing Bad Things to happen. To prevent this, check the size >> before copying the data block and return an error if it is too large. > > Good catch, we were relying on the drivers too much here. I think the > same fix is needed for the non-emulated case as well. Will have a look. > >> + if (msg[1].buf[0] > I2C_SMBUS_BLOCK_MAX) { >> + dev_err(&adapter->dev, >> + "Invalid block size returned: %d\n", >> + msg[1].buf[0]); >> + status = -EINVAL; > > I changed this to -EPROTO as described in > Documentation/i2c/fault-codes.rst. > > Applied to for-current, thanks! >
-- Måns Rullgård
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