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

[Jinjie Ruan]

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;


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