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thermal/core: Add NULL pointer check before using cooling device stats 

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>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1607367181-24589-1-git-send-email-manafm@codeaurora.org
This commit is contained in:
Manaf Meethalavalappu Pallikunhi 2020-12-08 00:23:01 +05:30 committed by Daniel Lezcano
parent a38fd87484
commit 2046a24ae1
1 changed files with 3 additions and 0 deletions
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3
drivers/thermal/thermal_sysfs.c
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@ -674,6 +674,9 @@ 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)