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> --- 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 | 16 +++++++++++----- 3 files changed, 26 insertions(+), 6 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..74f87f6ac390 100644 --- a/drivers/iio/inkern.c +++ b/drivers/iio/inkern.c @@ -560,9 +560,11 @@ static int iio_channel_read(struct iio_channel *chan, int *val, int *val2, vals, &val_len, info); *val = vals[0]; *val2 = vals[1]; - } else { + } else if (chan->indio_dev->info->read_raw) { ret = chan->indio_dev->info->read_raw(chan->indio_dev, chan->channel, val, val2, info); + } else { + return -EINVAL; } return ret; @@ -753,8 +755,10 @@ static int iio_channel_read_avail(struct iio_channel *chan, 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 (chan->indio_dev->info->read_avail) + return chan->indio_dev->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 +921,10 @@ 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); + if (chan->indio_dev->info->write_raw) + return chan->indio_dev->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, -- Julien Stephan <jstephan@xxxxxxxxxxxx>
