Patch "hwmon: (coretemp) Check for null before removing sysfs attrs" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    hwmon: (coretemp) Check for null before removing sysfs attrs

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hwmon-coretemp-check-for-null-before-removing-sysfs-.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 8c974f7fe1187020b913b83eae37054d27bca2a8
Author: Phil Auld <pauld@xxxxxxxxxx>
Date:   Thu Nov 17 11:23:13 2022 -0500

    hwmon: (coretemp) Check for null before removing sysfs attrs
    
    [ Upstream commit a89ff5f5cc64b9fe7a992cf56988fd36f56ca82a ]
    
    If coretemp_add_core() gets an error then pdata->core_data[indx]
    is already NULL and has been kfreed. Don't pass that to
    sysfs_remove_group() as that will crash in sysfs_remove_group().
    
    [Shortened for readability]
    [91854.020159] sysfs: cannot create duplicate filename '/devices/platform/coretemp.0/hwmon/hwmon2/temp20_label'
    <cpu offline>
    [91855.126115] BUG: kernel NULL pointer dereference, address: 0000000000000188
    [91855.165103] #PF: supervisor read access in kernel mode
    [91855.194506] #PF: error_code(0x0000) - not-present page
    [91855.224445] PGD 0 P4D 0
    [91855.238508] Oops: 0000 [#1] PREEMPT SMP PTI
    ...
    [91855.342716] RIP: 0010:sysfs_remove_group+0xc/0x80
    ...
    [91855.796571] Call Trace:
    [91855.810524]  coretemp_cpu_offline+0x12b/0x1dd [coretemp]
    [91855.841738]  ? coretemp_cpu_online+0x180/0x180 [coretemp]
    [91855.871107]  cpuhp_invoke_callback+0x105/0x4b0
    [91855.893432]  cpuhp_thread_fun+0x8e/0x150
    ...
    
    Fix this by checking for NULL first.
    
    Signed-off-by: Phil Auld <pauld@xxxxxxxxxx>
    Cc: linux-hwmon@xxxxxxxxxxxxxxx
    Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
    Cc: Jean Delvare <jdelvare@xxxxxxxx>
    Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20221117162313.3164803-1-pauld@xxxxxxxxxx
    Fixes: 199e0de7f5df3 ("hwmon: (coretemp) Merge pkgtemp with coretemp")
    Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index d2530f581186..65e06e18b8f0 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -533,6 +533,10 @@ static void coretemp_remove_core(struct platform_data *pdata, int indx)
 {
 	struct temp_data *tdata = pdata->core_data[indx];
 
+	/* if we errored on add then this is already gone */
+	if (!tdata)
+		return;
+
 	/* Remove the sysfs attributes */
 	sysfs_remove_group(&pdata->hwmon_dev->kobj, &tdata->attr_group);