[PATCH AUTOSEL 6.1 38/61] driver: iio: add missing checks on iio_info's callback access

Sasha Levin
2024-08-01T00:30:28Z

From: Julien Stephan <jstephan@baylibre.com>

[ Upstream commit c4ec8dedca961db056ec85cb7ca8c9f7e2e92252 ]

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@analog.com>
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Link: https://lore.kernel.org/r/20240530-iio-core-fix-segfault-v3-1-8b7cd2a03773@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 135a86fc94531..162845543efe0 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -767,9 +767,11 @@ 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;
@@ -851,6 +853,9 @@ 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 727e2ef66aa4b..14658b41c9bc6 100644
--- a/drivers/iio/industrialio-event.c
+++ b/drivers/iio/industrialio-event.c
@@ -283,6 +283,9 @@ 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);
@@ -298,6 +301,9 @@ 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));
@@ -316,6 +322,9 @@ 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 872fd5c241476..bd854e92c6f8c 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -561,6 +561,7 @@ 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;
@@ -572,15 +573,18 @@ 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;
@@ -800,11 +804,15 @@ 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,
@@ -935,8 +943,12 @@ 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,
--
2.43.0