UNAPPLIED: NACK: [SRU][F][PATCH 1/1] thermal/drivers/cpufreq_cooling: Fix slab OOB issue

[Stefan Bader]

On 25.03.24 15:41, Manuel Diewald wrote:
> On Thu, Mar 21, 2024 at 09:56:09AM -0500, Bethany Jamison wrote:
>> From: brian-sy yang <brian-sy.yang at mediatek.com>
>>
>> Slab OOB issue is scanned by KASAN in cpu_power_to_freq().
>> If power is limited below the power of OPP0 in EM table,
>> it will cause slab out-of-bound issue with negative array
>> index.
>>
>> Return the lowest frequency if limited power cannot found
>> a suitable OPP in EM table to fix this issue.
>>
>> Backtrace:
>> [<ffffffd02d2a37f0>] die+0x104/0x5ac
>> [<ffffffd02d2a5630>] bug_handler+0x64/0xd0
>> [<ffffffd02d288ce4>] brk_handler+0x160/0x258
>> [<ffffffd02d281e5c>] do_debug_exception+0x248/0x3f0
>> [<ffffffd02d284488>] el1_dbg+0x14/0xbc
>> [<ffffffd02d75d1d4>] __kasan_report+0x1dc/0x1e0
>> [<ffffffd02d75c2e0>] kasan_report+0x10/0x20
>> [<ffffffd02d75def8>] __asan_report_load8_noabort+0x18/0x28
>> [<ffffffd02e6fce5c>] cpufreq_power2state+0x180/0x43c
>> [<ffffffd02e6ead80>] power_actor_set_power+0x114/0x1d4
>> [<ffffffd02e6fac24>] allocate_power+0xaec/0xde0
>> [<ffffffd02e6f9f80>] power_allocator_throttle+0x3ec/0x5a4
>> [<ffffffd02e6ea888>] handle_thermal_trip+0x160/0x294
>> [<ffffffd02e6edd08>] thermal_zone_device_check+0xe4/0x154
>> [<ffffffd02d351cb4>] process_one_work+0x5e4/0xe28
>> [<ffffffd02d352f44>] worker_thread+0xa4c/0xfac
>> [<ffffffd02d360124>] kthread+0x33c/0x358
>> [<ffffffd02d289940>] ret_from_fork+0xc/0x18
>>
>> Fixes: 371a3bc79c11b ("thermal/drivers/cpufreq_cooling: Fix wrong frequency converted from power")
>> Signed-off-by: brian-sy yang <brian-sy.yang at mediatek.com>
>> Signed-off-by: Michael Kao <michael.kao at mediatek.com>
>> Reviewed-by: Lukasz Luba <lukasz.luba at arm.com>
>> Cc: stable at vger.kernel.org #v5.7
>> Signed-off-by: Daniel Lezcano <daniel.lezcano at linaro.org>
>> Link: https://lore.kernel.org/r/20201229050831.19493-1-michael.kao@mediatek.com
>> (backported from commit 34ab17cc6c2c1ac93d7e5d53bb972df9a968f085)
>> [bjamison: context conflict - fix commit changes the range of a for-loop from
>> [0, max_level] to (0, max_level], Focal's for-loop is set-up differently
>> than upstream, I changed the range from [0, max_level) to match the fix range]
>> CVE-2020-36776
>> Signed-off-by: Bethany Jamison <bethany.jamison at canonical.com>
>> ---
>>   drivers/thermal/cpu_cooling.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>> index 9d24bc05df0da..ba3df71bb877f 100644
>> --- a/drivers/thermal/cpu_cooling.c
>> +++ b/drivers/thermal/cpu_cooling.c
>> @@ -210,7 +210,7 @@ static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
>>   	int i;
>>   	struct freq_table *freq_table = cpufreq_cdev->freq_table;
>>   
>> -	for (i = 0; i < cpufreq_cdev->max_level; i++)
>> +	for (i = 1; i <= cpufreq_cdev->max_level; i++)
> 
> In the scenario that this patch is supposed to fix, where power <
> freq_table[0].power, this backport will access freq_table[i].frequency,
> where i == cpufreq_cdev->max_level + 1, resulting in an invalid memory
> access. Furthermore, by starting the loop at i == 1, the function will
> never return the frequency at index 0 of the table even if the
> corresponding power is below the limit.
> 
> I don't think bionic/focal are affected by the described out-of-bounds
> issue and this backport is not required.
> 
> cpu_power_to_freq() will return the highest frequency instead of the
> lowest in case power is limited below what is specified in the table for
> bionic/focal as opposed to later kernel series, but that is a separate
> issue. Applying this fix only makes sense if were to also backport the
> prerequisite changes that have been introduced in later kernel series,
> as far as I can tell.
> 
>>   		if (power >= freq_table[i].power)
>>   			break;
>>   
>> -- 
>> 2.34.1
>>
>>
>> -- 
>> kernel-team mailing list
>> kernel-team at lists.ubuntu.com
>> https://lists.ubuntu.com/mailman/listinfo/kernel-team
> 

Ok, I have dropped this patch from Focal for now.
-- 
- Stefan

-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_0xE8675DEECBEECEA3.asc
Type: application/pgp-keys
Size: 48643 bytes
Desc: OpenPGP public key
URL: <https://lists.ubuntu.com/archives/kernel-team/attachments/20240325/7fa97ddb/attachment-0001.key>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <https://lists.ubuntu.com/archives/kernel-team/attachments/20240325/7fa97ddb/attachment-0001.sig>