On Thu, 30 May 2024 11:22:46 +0200 Julien Stephan <jstephan@xxxxxxxxxxxx> wrote: > Some callbacks from iio_info structure are accessed without any check, so > if a driver doesn't implement them trying to access the corresponding > sysfs entries produce a kernel oops such as: > > [ 2203.527791] Unable to handle kernel NULL pointer dereference at virtual address 00000000 when execute > [...] > [ 2203.783416] Call trace: > [ 2203.783429] iio_read_channel_info_avail from dev_attr_show+0x18/0x48 > [ 2203.789807] dev_attr_show from sysfs_kf_seq_show+0x90/0x120 > [ 2203.794181] sysfs_kf_seq_show from seq_read_iter+0xd0/0x4e4 > [ 2203.798555] seq_read_iter from vfs_read+0x238/0x2a0 > [ 2203.802236] vfs_read from ksys_read+0xa4/0xd4 > [ 2203.805385] ksys_read from ret_fast_syscall+0x0/0x54 > [ 2203.809135] Exception stack(0xe0badfa8 to 0xe0badff0) > [ 2203.812880] dfa0: 00000003 b6f10f80 00000003 b6eab000 00020000 00000000 > [ 2203.819746] dfc0: 00000003 b6f10f80 7ff00000 00000003 00000003 00000000 00020000 00000000 > [ 2203.826619] dfe0: b6e1bc88 bed80958 b6e1bc94 b6e1bcb0 > [ 2203.830363] Code: bad PC value > [ 2203.832695] ---[ end trace 0000000000000000 ]--- > > Reviewed-by: Nuno Sa <nuno.sa@xxxxxxxxxx> > Signed-off-by: Julien Stephan <jstephan@xxxxxxxxxxxx> Dropped v2 and picked this one up. Oops. Jonathan > --- > Changes in v3: > - Use local variable in inkern.c to reduce long lines > - Pick up Nuno reviewed-by tag > - Link to v2: https://lore.kernel.org/r/20240529-iio-core-fix-segfault-v2-1-7b5a5fa6853f@xxxxxxxxxxxx > > Changes in v2: > - crop dmesg log to show only pertinent info and reduce commit message > - Link to v1: https://lore.kernel.org/r/20240529-iio-core-fix-segfault-v1-1-7ff1ba881d38@xxxxxxxxxxxx > --- > drivers/iio/industrialio-core.c | 7 ++++++- > drivers/iio/industrialio-event.c | 9 +++++++++ > drivers/iio/inkern.c | 32 ++++++++++++++++++++++---------- > 3 files changed, 37 insertions(+), 11 deletions(-) > > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c > index fa7cc051b4c4..2f185b386949 100644 > --- a/drivers/iio/industrialio-core.c > +++ b/drivers/iio/industrialio-core.c > @@ -758,9 +758,11 @@ static ssize_t iio_read_channel_info(struct device *dev, > INDIO_MAX_RAW_ELEMENTS, > vals, &val_len, > this_attr->address); > - else > + else if (indio_dev->info->read_raw) > ret = indio_dev->info->read_raw(indio_dev, this_attr->c, > &vals[0], &vals[1], this_attr->address); > + else > + return -EINVAL; > > if (ret < 0) > return ret; > @@ -842,6 +844,9 @@ static ssize_t iio_read_channel_info_avail(struct device *dev, > int length; > int type; > > + if (!indio_dev->info->read_avail) > + return -EINVAL; > + > ret = indio_dev->info->read_avail(indio_dev, this_attr->c, > &vals, &type, &length, > this_attr->address); > diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c > index 910c1f14abd5..a64f8fbac597 100644 > --- a/drivers/iio/industrialio-event.c > +++ b/drivers/iio/industrialio-event.c > @@ -285,6 +285,9 @@ static ssize_t iio_ev_state_store(struct device *dev, > if (ret < 0) > return ret; > > + if (!indio_dev->info->write_event_config) > + return -EINVAL; > + > ret = indio_dev->info->write_event_config(indio_dev, > this_attr->c, iio_ev_attr_type(this_attr), > iio_ev_attr_dir(this_attr), val); > @@ -300,6 +303,9 @@ static ssize_t iio_ev_state_show(struct device *dev, > struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); > int val; > > + if (!indio_dev->info->read_event_config) > + return -EINVAL; > + > val = indio_dev->info->read_event_config(indio_dev, > this_attr->c, iio_ev_attr_type(this_attr), > iio_ev_attr_dir(this_attr)); > @@ -318,6 +324,9 @@ static ssize_t iio_ev_value_show(struct device *dev, > int val, val2, val_arr[2]; > int ret; > > + if (!indio_dev->info->read_event_value) > + return -EINVAL; > + > ret = indio_dev->info->read_event_value(indio_dev, > this_attr->c, iio_ev_attr_type(this_attr), > iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr), > diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c > index 52d773261828..77cf1f22df31 100644 > --- a/drivers/iio/inkern.c > +++ b/drivers/iio/inkern.c > @@ -543,6 +543,7 @@ EXPORT_SYMBOL_GPL(devm_iio_channel_get_all); > static int iio_channel_read(struct iio_channel *chan, int *val, int *val2, > enum iio_chan_info_enum info) > { > + const struct iio_info *iio_info = chan->indio_dev->info; > int unused; > int vals[INDIO_MAX_RAW_ELEMENTS]; > int ret; > @@ -554,15 +555,18 @@ static int iio_channel_read(struct iio_channel *chan, int *val, int *val2, > if (!iio_channel_has_info(chan->channel, info)) > return -EINVAL; > > - if (chan->indio_dev->info->read_raw_multi) { > - ret = chan->indio_dev->info->read_raw_multi(chan->indio_dev, > - chan->channel, INDIO_MAX_RAW_ELEMENTS, > - vals, &val_len, info); > + if (iio_info->read_raw_multi) { > + ret = iio_info->read_raw_multi(chan->indio_dev, > + chan->channel, > + INDIO_MAX_RAW_ELEMENTS, > + vals, &val_len, info); > *val = vals[0]; > *val2 = vals[1]; > + } else if (iio_info->read_raw) { > + ret = iio_info->read_raw(chan->indio_dev, > + chan->channel, val, val2, info); > } else { > - ret = chan->indio_dev->info->read_raw(chan->indio_dev, > - chan->channel, val, val2, info); > + return -EINVAL; > } > > return ret; > @@ -750,11 +754,15 @@ static int iio_channel_read_avail(struct iio_channel *chan, > const int **vals, int *type, int *length, > enum iio_chan_info_enum info) > { > + const struct iio_info *iio_info = chan->indio_dev->info; > + > if (!iio_channel_has_available(chan->channel, info)) > return -EINVAL; > > - return chan->indio_dev->info->read_avail(chan->indio_dev, chan->channel, > - vals, type, length, info); > + if (iio_info->read_avail) > + return iio_info->read_avail(chan->indio_dev, chan->channel, > + vals, type, length, info); > + return -EINVAL; > } > > int iio_read_avail_channel_attribute(struct iio_channel *chan, > @@ -917,8 +925,12 @@ EXPORT_SYMBOL_GPL(iio_get_channel_type); > static int iio_channel_write(struct iio_channel *chan, int val, int val2, > enum iio_chan_info_enum info) > { > - return chan->indio_dev->info->write_raw(chan->indio_dev, > - chan->channel, val, val2, info); > + const struct iio_info *iio_info = chan->indio_dev->info; > + > + if (iio_info->write_raw) > + return iio_info->write_raw(chan->indio_dev, > + chan->channel, val, val2, info); > + return -EINVAL; > } > > int iio_write_channel_attribute(struct iio_channel *chan, int val, int val2, > > --- > base-commit: 409b6d632f5078f3ae1018b6e43c32f2e12f6736 > change-id: 20240528-iio-core-fix-segfault-aa74be7eee4a > > Best regards,
