On 04/12/2020 20:09, Manaf Meethalavalappu Pallikunhi wrote:
> There is a possible chance that some cooling device stats buffer
> allocation fails due to very high cooling device max state value.
> Later cooling device update or cooling stats sysfs will try to
> access stats data for the same cooling device. It will lead to
> NULL pointer dereference issue.
>
> Add a NULL pointer check before accessing thermal cooling device
> stats data. It fixes the following bug
Why not create the 'stats' dir if the setup fails ?
> [ 26.812833] Unable to handle kernel NULL pointer dereference at virtual
> address 0000000000000004
> [ 27.122960] Call trace:
> [ 27.122963] do_raw_spin_lock+0x18/0xe8
> [ 27.122966] _raw_spin_lock+0x24/0x30
> [ 27.128157] thermal_cooling_device_stats_update+0x24/0x98
> [ 27.128162] cur_state_store+0x88/0xb8
> [ 27.128166] dev_attr_store+0x40/0x58
> [ 27.128169] sysfs_kf_write+0x50/0x68
> [ 27.133358] kernfs_fop_write+0x12c/0x1c8
> [ 27.133362] __vfs_write+0x54/0x160
> [ 27.152297] vfs_write+0xcc/0x188
> [ 27.157132] ksys_write+0x78/0x108
> [ 27.162050] ksys_write+0xf8/0x108
> [ 27.166968] __arm_smccc_hvc+0x158/0x4b0
> [ 27.166973] __arm_smccc_hvc+0x9c/0x4b0
> [ 27.186005] el0_svc+0x8/0xc
>
> Signed-off-by: Manaf Meethalavalappu Pallikunhi <man...@codeaurora.org>
> ---
> drivers/thermal/thermal_sysfs.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
> index 473449b..a5e4855 100644
> --- a/drivers/thermal/thermal_sysfs.c
> +++ b/drivers/thermal/thermal_sysfs.c
> @@ -827,6 +827,9 @@ void thermal_cooling_device_stats_update(struct
> thermal_cooling_device *cdev,
> {
> struct cooling_dev_stats *stats = cdev->stats;
>
> + if (!stats)
> + return;
> +
> spin_lock(&stats->lock);
>
> if (stats->state == new_state)
> @@ -848,6 +851,9 @@ static ssize_t total_trans_show(struct device *dev,
> struct cooling_dev_stats *stats = cdev->stats;
> int ret;
>
> + if (!stats)
> + return -ENODEV;
> +
> spin_lock(&stats->lock);
> ret = sprintf(buf, "%u\n", stats->total_trans);
> spin_unlock(&stats->lock);
> @@ -864,6 +870,9 @@ time_in_state_ms_show(struct device *dev, struct
> device_attribute *attr,
> ssize_t len = 0;
> int i;
>
> + if (!stats)
> + return -ENODEV;
> +
> spin_lock(&stats->lock);
> update_time_in_state(stats);
>
> @@ -882,8 +891,12 @@ reset_store(struct device *dev, struct device_attribute
> *attr, const char *buf,
> {
> struct thermal_cooling_device *cdev = to_cooling_device(dev);
> struct cooling_dev_stats *stats = cdev->stats;
> - int i, states = stats->max_states;
> + int i, states;
> +
> + if (!stats)
> + return -ENODEV;
>
> + states = stats->max_states;
> spin_lock(&stats->lock);
>
> stats->total_trans = 0;
> @@ -907,6 +920,9 @@ static ssize_t trans_table_show(struct device *dev,
> ssize_t len = 0;
> int i, j;
>
> + if (!stats)
> + return -ENODEV;
> +
> len += snprintf(buf + len, PAGE_SIZE - len, " From : To\n");
> len += snprintf(buf + len, PAGE_SIZE - len, " : ");
> for (i = 0; i < stats->max_states; i++) {
>
--
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