linux-kernel - Re: [PATCH v5] crash: Fix crash memory reserve exceed system memory bug

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Message-ID: <Zp8859QW+YV1KqQ9@MiWiFi-R3L-srv>
Date: Tue, 23 Jul 2024 13:17:27 +0800
From: Baoquan He <bhe@...hat.com>
To: Jinjie Ruan <ruanjinjie@...wei.com>
Cc: vgoyal@...hat.com, dyoung@...hat.com, paul.walmsley@...ive.com,
	palmer@...belt.com, aou@...s.berkeley.edu, rppt@...nel.org,
	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5] crash: Fix crash memory reserve exceed system memory
 bug

On 07/23/24 at 10:07am, Jinjie Ruan wrote:
> On x86_32 Qemu machine with 1GB memory, the cmdline "crashkernel=4G" is ok
> as below:
> 	crashkernel reserved: 0x0000000020000000 - 0x0000000120000000 (4096 MB)
> 
> It's similar on other architectures, such as ARM32 and RISCV32.
> 
> 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 crash_size is greater than system RAM size and
> return error if so.
> 
> After this patch, there is no above confusing reserve success info.
> 
> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
> Suggested-by: Baoquan He <bhe@...hat.com>
> Suggested-by: Mike Rapoport <rppt@...nel.org>


My Suggested-by can be taken off because I suggested to check the parsed
value after parse_crashkernel(), Mike's suggestion is better.

For this version,

Acked-by: Baoquan He <bhe@...hat.com>

> ---
> v5:
> - Fix it in common parse_crashkernel() instead of per-arch.
> - Add suggested-by.
> 
> v4:
> - Update the warn info to align with parse_crashkernel_mem().
> - Rebased on the "ARM: Use generic interface to simplify crashkernel
>   reservation" patch.
> - Also fix for riscv32.
> - Update the commit message.
> 
> v3:
> - Handle the check in reserve_crashkernel() Baoquan suggested.
> - Split x86_32 and arm32.
> - Add Suggested-by.
> - Drop the wrong fix tag.
> 
> v2:
> - Also fix for x86_32.
> - Update the fix method.
> - Peel off the other two patches.
> - Update the commit message.
> ---
>  kernel/crash_reserve.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c
> index ad5b3f2c5487..5387269114f6 100644
> --- a/kernel/crash_reserve.c
> +++ b/kernel/crash_reserve.c
> @@ -335,6 +335,9 @@ int __init parse_crashkernel(char *cmdline,
>  	if (!*crash_size)
>  		ret = -EINVAL;
>  
> +	if (*crash_size >= system_ram)
> +		ret = -EINVAL;
> +
>  	return ret;
>  }
>  
> -- 
> 2.34.1
>