linux-kernel - Re: [f2fs-dev] [PATCH] f2fs-tools: fix overflow bug of start_sector when computing zone_align_start

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Message-ID: <bc79c076-1106-54c6-ba43-040669186997@huawei.com>
Date:   Sun, 27 May 2018 21:41:49 +0800
From:   Yunlong Song <yunlong.song@...wei.com>
To:     Junling Zheng <zhengjunling@...wei.com>, <jaegeuk@...nel.org>,
        <chao@...nel.org>, <yuchao0@...wei.com>, <yunlong.song@...oud.com>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>, <miaoxie@...wei.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs-tools: fix overflow bug of start_sector
 when computing zone_align_start_offset

Just keep it same with u_int64_t defined in mkfs/f2fs_format.c, and 
c.start_sector * c.sector_size
may be u32 overflow, so add (u_int64_t) before c.start_sector * 
c.sector_size and change the target
value zone_align_start_offset to (u_int64_t).

On 2018/5/26 19:27, Junling Zheng wrote:
> No neet to change zone_align_start_offset to u64, because zone_align_start_offset is always
> smaller than zone_size_bytes, which is u32.
>
> Thanks,
> Junling
>
> On 2018/5/26 16:09, Yunlong Song wrote:
>> zone_align_start_offset should be u64, but config.start_sector is u32,
>> so it may be overflow when computing zone_align_start_offset.
>>
>> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
>> ---
>>   fsck/resize.c      | 7 ++++---
>>   mkfs/f2fs_format.c | 4 ++--
>>   2 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/fsck/resize.c b/fsck/resize.c
>> index d285dd7..8ac7d45 100644
>> --- a/fsck/resize.c
>> +++ b/fsck/resize.c
>> @@ -11,7 +11,8 @@
>>   
>>   static int get_new_sb(struct f2fs_super_block *sb)
>>   {
>> -	u_int32_t zone_size_bytes, zone_align_start_offset;
>> +	u_int32_t zone_size_bytes;
>> +	u_int64_t zone_align_start_offset;
>>   	u_int32_t blocks_for_sit, blocks_for_nat, blocks_for_ssa;
>>   	u_int32_t sit_segments, nat_segments, diff, total_meta_segments;
>>   	u_int32_t total_valid_blks_available;
>> @@ -27,10 +28,10 @@ static int get_new_sb(struct f2fs_super_block *sb)
>>   
>>   	zone_size_bytes = segment_size_bytes * segs_per_zone;
>>   	zone_align_start_offset =
>> -		(c.start_sector * c.sector_size +
>> +		((u_int64_t) c.start_sector * c.sector_size +
>>   		2 * F2FS_BLKSIZE + zone_size_bytes - 1) /
>>   		zone_size_bytes * zone_size_bytes -
>> -		c.start_sector * c.sector_size;
>> +		(u_int64_t) c.start_sector * c.sector_size;
>>   
>>   	set_sb(segment_count, (c.target_sectors * c.sector_size -
>>   				zone_align_start_offset) / segment_size_bytes /
>> diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
>> index 0a99a77..f045e23 100644
>> --- a/mkfs/f2fs_format.c
>> +++ b/mkfs/f2fs_format.c
>> @@ -212,10 +212,10 @@ static int f2fs_prepare_super_block(void)
>>   	set_sb(block_count, c.total_sectors >> log_sectors_per_block);
>>   
>>   	zone_align_start_offset =
>> -		(c.start_sector * c.sector_size +
>> +		((u_int64_t) c.start_sector * c.sector_size +
>>   		2 * F2FS_BLKSIZE + zone_size_bytes - 1) /
>>   		zone_size_bytes * zone_size_bytes -
>> -		c.start_sector * c.sector_size;
>> +		(u_int64_t) c.start_sector * c.sector_size;
>>   
>>   	if (c.start_sector % c.sectors_per_blk) {
>>   		MSG(1, "\t%s: Align start sector number to the page unit\n",
>>
>
>
> .
>

-- 
Thanks,
Yunlong Song