[PATCH v2] drivers: thermal: Add NULL pointer check before using cooling device stats

[PATCH v2] drivers: thermal: Add NULL pointer check before using cooling device stats

[Manaf Meethalavalappu Pallikunhi]

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 sysfs can 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

[ 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 <manafm@codeaurora.org>
---
 drivers/thermal/thermal_sysfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index 473449b..10ca4f5 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)
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v2] drivers: thermal: Add NULL pointer check before using cooling device stats

[manafm]

On 2020-12-08 00:23, Manaf Meethalavalappu Pallikunhi wrote:

Gentle reminder..

> 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 sysfs can 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
> 
> [ 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 <manafm@codeaurora.org>
> ---
>  drivers/thermal/thermal_sysfs.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/thermal/thermal_sysfs.c 
> b/drivers/thermal/thermal_sysfs.c
> index 473449b..10ca4f5 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)

Re: [PATCH v2] drivers: thermal: Add NULL pointer check before using cooling device stats

[Daniel Lezcano]

On 05/03/2021 18:24, manafm@codeaurora.org wrote:
> On 2020-12-08 00:23, Manaf Meethalavalappu Pallikunhi wrote:
> 
> Gentle reminder..

Thanks for the reminder, I'll pick it for the next -rc

  -- Daniel


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