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Message-ID: <e1a8ff6ee52e8c8d0c5b0704d7b6b26088d0925a.camel@analog.com>
Date: Wed, 15 Apr 2020 05:47:14 +0000
From: "Ardelean, Alexandru" <alexandru.Ardelean@...log.com>
To: "jeremyfertic@...il.com" <jeremyfertic@...il.com>
CC: "Tachici, Alexandru" <Alexandru.Tachici@...log.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] iio: adc: ad7192: fix null pointer de-reference
crash during probe
On Mon, 2020-04-13 at 16:06 -0600, Jeremy Fertic wrote:
> [External]
>
> On Mon, Apr 13, 2020 at 11:20:43AM +0300, Alexandru Ardelean wrote:
> > When the 'spi_device_id' table was removed, it omitted to cleanup/fix the
> > assignment:
> > 'indio_dev->name = spi_get_device_id(spi)->name;'
> >
> > After that patch 'spi_get_device_id(spi)' returns NULL, so this crashes
> > during probe with null de-ref.
> >
> > This change fixes this by introducing an ad7192_chip_info struct, and
> > defines all part-names [that should be assigned to indio_dev->name] in a
> > 'ad7192_chip_info_tbl' table.
> >
> > With this change, the old 'st->devid' is also moved to be a
> > 'chip_info->chip_id'. And the old 'ID_AD719X' macros have been renamed to
> > 'CHIPID_AD719X'. Tld identifiers have been re-purposed to be enum/index
> > values in the new 'ad7192_chip_info_tbl'.
> >
> > This should fix the bug, and maintain the ABI for the 'indio_dev->name'
> > field.
> >
> > Fixes: 66614ab2be38 ("staging: iio: adc: ad7192: removed spi_device_id")
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> > ---
> >
> > Changelog v2 -> v3:
> > * reworked patch to introduce a chip_info struct for the part-name
> > * added 2nd patch to move of-table closer to the end of the file; this
> > patch is more cosmetic; has no fixes tag, but is on top of the previous
> >
> > Changelog v1 -> v2:
> > * fix colon for Fixes tag
> > * updated commit title a bit; to make it longer
> >
> > drivers/iio/adc/ad7192.c | 61 ++++++++++++++++++++++++++++++----------
> > 1 file changed, 46 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
> > index 8ec28aa8fa8a..7e8662c5cb0e 100644
> > --- a/drivers/iio/adc/ad7192.c
> > +++ b/drivers/iio/adc/ad7192.c
> > @@ -125,10 +125,10 @@
> > #define AD7193_CH_AINCOM 0x600 /* AINCOM - AINCOM */
> >
> > /* ID Register Bit Designations (AD7192_REG_ID) */
> > -#define ID_AD7190 0x4
> > -#define ID_AD7192 0x0
> > -#define ID_AD7193 0x2
> > -#define ID_AD7195 0x6
> > +#define CHIPID_AD7190 0x4
> > +#define CHIPID_AD7192 0x0
> > +#define CHIPID_AD7193 0x2
> > +#define CHIPID_AD7195 0x6
> > #define AD7192_ID_MASK 0x0F
> >
> > /* GPOCON Register Bit Designations (AD7192_REG_GPOCON) */
> > @@ -161,7 +161,20 @@ enum {
> > AD7192_SYSCALIB_FULL_SCALE,
> > };
> >
> > +enum {
> > + ID_AD7190,
> > + ID_AD7192,
> > + ID_AD7193,
> > + ID_AD7195,
> > +};
> > +
> > +struct ad7192_chip_info {
> > + unsigned int chip_id;
> > + const char *name;
> > +};
> > +
> > struct ad7192_state {
> > + const struct ad7192_chip_info *chip_info;
> > struct regulator *avdd;
> > struct regulator *dvdd;
> > struct clk *mclk;
> > @@ -172,7 +185,6 @@ struct ad7192_state {
> > u32 conf;
> > u32 scale_avail[8][2];
> > u8 gpocon;
> > - u8 devid;
> > u8 clock_sel;
> > struct mutex lock; /* protect sensor state */
> > u8 syscalib_mode[8];
> > @@ -348,7 +360,7 @@ static int ad7192_setup(struct ad7192_state *st, struct
> > device_node *np)
> >
> > id &= AD7192_ID_MASK;
> >
> > - if (id != st->devid)
> > + if (id != st->chip_info->chip_id)
> > dev_warn(&st->sd.spi->dev, "device ID query failed (0x%X)\n",
> > id);
> >
> > @@ -363,7 +375,7 @@ static int ad7192_setup(struct ad7192_state *st, struct
> > device_node *np)
> > st->mode |= AD7192_MODE_REJ60;
> >
> > refin2_en = of_property_read_bool(np, "adi,refin2-pins-enable");
> > - if (refin2_en && st->devid != ID_AD7195)
> > + if (refin2_en && st->chip_info->chip_id != CHIPID_AD7195)
> > st->conf |= AD7192_CONF_REFSEL;
> >
> > st->conf &= ~AD7192_CONF_CHOP;
> > @@ -859,11 +871,30 @@ static const struct iio_chan_spec ad7193_channels[] =
> > {
> > IIO_CHAN_SOFT_TIMESTAMP(14),
> > };
> >
> > +static const struct ad7192_chip_info ad7192_chip_info_tbl[] = {
> > + [ID_AD7190] = {
> > + .chip_id = CHIPID_AD7190,
> > + .name = "ad7190",
> > + },
> > + [ID_AD7192] = {
> > + .chip_id = CHIPID_AD7192,
> > + .name = "ad7192",
> > + },
> > + [ID_AD7193] = {
> > + .chip_id = CHIPID_AD7193,
> > + .name = "ad7193",
> > + },
> > + [ID_AD7195] = {
> > + .chip_id = CHIPID_AD7195,
> > + .name = "ad7195",
> > + },
> > +};
> > +
> > static int ad7192_channels_config(struct iio_dev *indio_dev)
> > {
> > struct ad7192_state *st = iio_priv(indio_dev);
> >
> > - switch (st->devid) {
> > + switch (st->chip_info->chip_id) {
> > case ID_AD7193:
>
> Would it be better to change this to CHIPID_AD7193? It looks like it works
> the way you have it, but only by coincidence since it happens to be true
> that ID_AD7193 == CHIPID_AD7193.
Thanks for catching this.
I'll fix up in a V3.
>
> Jeremy
>
> > indio_dev->channels = ad7193_channels;
> > indio_dev->num_channels = ARRAY_SIZE(ad7193_channels);
> > @@ -878,10 +909,10 @@ static int ad7192_channels_config(struct iio_dev
> > *indio_dev)
> > }
> >
> > static const struct of_device_id ad7192_of_match[] = {
> > - { .compatible = "adi,ad7190", .data = (void *)ID_AD7190 },
> > - { .compatible = "adi,ad7192", .data = (void *)ID_AD7192 },
> > - { .compatible = "adi,ad7193", .data = (void *)ID_AD7193 },
> > - { .compatible = "adi,ad7195", .data = (void *)ID_AD7195 },
> > + { .compatible = "adi,ad7190", .data = &ad7192_chip_info_tbl[ID_AD7190]
> > },
> > + { .compatible = "adi,ad7192", .data = &ad7192_chip_info_tbl[ID_AD7192]
> > },
> > + { .compatible = "adi,ad7193", .data = &ad7192_chip_info_tbl[ID_AD7193]
> > },
> > + { .compatible = "adi,ad7195", .data = &ad7192_chip_info_tbl[ID_AD7195]
> > },
> > {}
> > };
> > MODULE_DEVICE_TABLE(of, ad7192_of_match);
> > @@ -938,16 +969,16 @@ static int ad7192_probe(struct spi_device *spi)
> > }
> >
> > spi_set_drvdata(spi, indio_dev);
> > - st->devid = (unsigned long)of_device_get_match_data(&spi->dev);
> > + st->chip_info = of_device_get_match_data(&spi->dev);
> > indio_dev->dev.parent = &spi->dev;
> > - indio_dev->name = spi_get_device_id(spi)->name;
> > + indio_dev->name = st->chip_info->name;
> > indio_dev->modes = INDIO_DIRECT_MODE;
> >
> > ret = ad7192_channels_config(indio_dev);
> > if (ret < 0)
> > goto error_disable_dvdd;
> >
> > - if (st->devid == ID_AD7195)
> > + if (st->chip_info->chip_id == CHIPID_AD7195)
> > indio_dev->info = &ad7195_info;
> > else
> > indio_dev->info = &ad7192_info;
> > --
> > 2.17.1
> >
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