linux-kernel - Re: [PATCH v2 4/4] kexec_file: Fix the issue of mismatch between loop variable types

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Message-ID: <DB8D55DA58E28E7A+e01fbd66-c45e-40f1-9d4e-44f18b04a716@uniontech.com>
Date: Wed, 5 Nov 2025 15:06:49 +0800
From: Qiang Ma <maqianga@...ontech.com>
To: Baoquan He <bhe@...hat.com>
Cc: akpm@...ux-foundation.org, kexec@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] kexec_file: Fix the issue of mismatch between loop
 variable types


在 2025/11/5 14:56, Baoquan He 写道:
> On 11/05/25 at 11:47am, Qiang Ma wrote:
>> 在 2025/11/5 11:05, Baoquan He 写道:
>>> On 11/03/25 at 02:34pm, Qiang Ma wrote:
>>>> The type of the struct kimage member variable nr_segments is unsigned long.
>>>> Correct the loop variable i and the print format specifier type.
>>> I can't see what's meaningful with this change. nr_segments is unsigned
>>> long, but it's the range 'i' will loop. If so, we need change all for
>>> loop of the int iterator.
>> If image->nr_segments is large enough, 'i' overflow causes an infinite loop.
> Please check kexec_add_buffer(), there's checking for the value which
> upper limit is restricted to 16.
>
>          if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
>                  return -EINVAL;
Oh, then this patch is really not necessary.
>>>> Signed-off-by: Qiang Ma <maqianga@...ontech.com>
>>>> ---
>>>>    kernel/kexec_file.c | 5 +++--
>>>>    1 file changed, 3 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
>>>> index 4a24aadbad02..7afdaa0efc50 100644
>>>> --- a/kernel/kexec_file.c
>>>> +++ b/kernel/kexec_file.c
>>>> @@ -366,7 +366,8 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
>>>>    	int image_type = (flags & KEXEC_FILE_ON_CRASH) ?
>>>>    			 KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
>>>>    	struct kimage **dest_image, *image;
>>>> -	int ret = 0, i;
>>>> +	int ret = 0;
>>>> +	unsigned long i;
>>>>    	/* We only trust the superuser with rebooting the system. */
>>>>    	if (!kexec_load_permitted(image_type))
>>>> @@ -432,7 +433,7 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
>>>>    		struct kexec_segment *ksegment;
>>>>    		ksegment = &image->segment[i];
>>>> -		kexec_dprintk("segment[%d]: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
>>>> +		kexec_dprintk("segment[%lu]: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
>>>>    			      i, ksegment->buf, ksegment->bufsz, ksegment->mem,
>>>>    			      ksegment->memsz);
>>>> -- 
>>>> 2.20.1
>>>>
>