Re: [PATCH v4 3/3] riscv: kdump: Fix crash memory reserve exceed system memory bug

[Jinjie Ruan]

On 2024/7/22 15:23, Mike Rapoport wrote:
> On Mon, Jul 22, 2024 at 03:08:29PM +0800, Jinjie Ruan wrote:
>>
>>
>> On 2024/7/22 14:38, Mike Rapoport wrote:
>>> Hi,
>>>
>>> On Mon, Jul 22, 2024 at 11:57:01AM +0800, Jinjie Ruan wrote:
>>>> Similar with x86_32, on Riscv32 Qemu "virt" machine with 1GB memory, the
>>>> crash kernel "crashkernel=4G" is ok as below:
>>>> 	crashkernel reserved: 0x00000000bf400000 - 0x00000001bf400000 (4096 MB)
>>>>
>>>> The cause is that the crash_size is parsed and printed with "unsigned long
>>>> long" data type which is 8 bytes but allocated used with "phys_addr_t"
>>>> which is 4 bytes in memblock_phys_alloc_range().
>>>>
>>>> Fix it by checking if the crash_size is greater than system RAM size and
>>>> warn out as parse_crashkernel_mem() do it if so.
>>>>
>>>> After this patch, it fails and there is no above confusing reserve
>>>> success info.
>>>>
>>>> Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
>>>> ---
>>>>  arch/riscv/mm/init.c | 5 +++++
>>>>  1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>>>> index bfa2dea95354..5d66a4937fcd 100644
>>>> --- a/arch/riscv/mm/init.c
>>>> +++ b/arch/riscv/mm/init.c
>>>> @@ -1381,6 +1381,11 @@ static void __init arch_reserve_crashkernel(void)
>>>>  	if (ret)
>>>>  		return;
>>>>  
>>>> +	if (crash_size >= memblock_phys_mem_size()) {
>>>> +		pr_warn("Crashkernel: invalid size.");
>>>> +		return;
>>>> +	}
>>>> +
>>>
>>> What the point of adding three identical checks right after the call to
>>> parse_crashkernel()?
>>>
>>> This check should be there and parse_crashkernel() should return error in
>>> this case.
>>
>> Hi, Mike
>>
>> How about the folling rough patch?
>>
>> --- a/kernel/crash_reserve.c
>> +++ b/kernel/crash_reserve.c
>> @@ -313,7 +313,7 @@ int __init parse_crashkernel(char *cmdline,
>>         if (high && ret == -ENOENT) {
>>                 ret = __parse_crashkernel(cmdline, 0, crash_size,
>>                                 crash_base, suffix_tbl[SUFFIX_HIGH]);
>> -               if (ret || !*crash_size)
>> +               if (ret || !*crash_size || crash_size >= system_ram)
>>                         return -EINVAL;
>>
>>                 /*
>> @@ -332,7 +332,7 @@ int __init parse_crashkernel(char *cmdline,
>>                 *high = true;
>>         }
>>  #endif
>> -       if (!*crash_size)
>> +       if (!*crash_size || crash_size >= system_ram)
>>                 ret = -EINVAL;
>>
> 
> Why no simply
> 
> diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c
> index 5b2722a93a48..64312709877d 100644
> --- a/kernel/crash_reserve.c
> +++ b/kernel/crash_reserve.c
> @@ -336,6 +336,9 @@ int __init parse_crashkernel(char *cmdline,
>  	if (!*crash_size)
>  		ret = -EINVAL;
>  
> +	if (*crash_size >= system_ram)
> +		ret = -EINVAL;
> +
>  	return ret;

This is good, thank you!

>  }
>  
>  
>>>
>>>>  	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
>>>>  				    low_size, high);
>>>>  }
>>>> -- 
>>>> 2.34.1
>>>>
>>>
>