linux-kernel - Re: [PATCH v5] f2fs: fix potential .flags overflow on 32bit architecture

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Message-ID: <e811683f-8906-a152-5d76-cd284fca6a2f@huawei.com>
Date:   Tue, 24 Mar 2020 14:13:28 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Joe Perches <joe@...ches.com>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>
Subject: Re: [PATCH v5] f2fs: fix potential .flags overflow on 32bit
 architecture

On 2020/3/23 23:10, Jaegeuk Kim wrote:
> On 03/23, Joe Perches wrote:
>> On Mon, 2020-03-23 at 11:18 +0800, Chao Yu wrote:
>>> f2fs_inode_info.flags is unsigned long variable, it has 32 bits
>>> in 32bit architecture, since we introduced FI_MMAP_FILE flag
>>> when we support data compression, we may access memory cross
>>> the border of .flags field, corrupting .i_sem field, result in
>>> below deadlock.
>> []
>>> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
>> []
>>> @@ -362,7 +362,7 @@ static int do_read_inode(struct inode *inode)
>>>  	fi->i_flags = le32_to_cpu(ri->i_flags);
>>>  	if (S_ISREG(inode->i_mode))
>>>  		fi->i_flags &= ~F2FS_PROJINHERIT_FL;
>>> -	fi->flags = 0;
>>> +	bitmap_zero(fi->flags, BITS_TO_LONGS(FI_MAX));
>>
>> Sorry, I misled you here, this should be
>>
>> 	bitmap_zero(fi->flags, FI_MAX);

Oh, I missed to check that as well. :(

> 
> Thanks, I applied this directly in the f2fs tree.

Thanks for the help.

Thanks,

> .
>