From: Chao Yu <yuchao0@huawei.com>
To: Joe Perches <joe@perches.com>, <jaegeuk@kernel.org>
Cc: <linux-f2fs-devel@lists.sourceforge.net>,
<linux-kernel@vger.kernel.org>, <chao@kernel.org>
Subject: Re: [PATCH v4] f2fs: fix potential .flags overflow on 32bit architecture
Date: Mon, 23 Mar 2020 11:22:01 +0800 [thread overview]
Message-ID: <aaa065c4-5c15-38a1-f2ea-73b4226fb203@huawei.com> (raw)
In-Reply-To: <8d435607bd79f518bd9420d68894ddda521bac5a.camel@perches.com>
On 2020/3/23 10:57, Joe Perches wrote:
> On Mon, 2020-03-23 at 10:41 +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/f2fs.h b/fs/f2fs/f2fs.h
> []
>> @@ -682,6 +682,47 @@ enum {
> []
>> +/* used for f2fs_inode_info->flags */
>> +enum {
> []
>> + FI_MAX, /* max flag, never be used */
>> +};
>> +
>> +/* f2fs_inode_info.flags array size */
>> +#define FI_ARRAY_SIZE (BITS_TO_LONGS(FI_MAX))
>
> Perhaps FI_ARRAY_SIZE isn't necessary.
>
>> +
>> struct f2fs_inode_info {
>> struct inode vfs_inode; /* serve a vfs inode */
>> unsigned long i_flags; /* keep an inode flags for ioctl */
>> @@ -694,7 +735,7 @@ struct f2fs_inode_info {
>> umode_t i_acl_mode; /* keep file acl mode temporarily */
>>
>> /* Use below internally in f2fs*/
>> - unsigned long flags; /* use to pass per-file flags */
>> + unsigned long flags[FI_ARRAY_SIZE]; /* use to pass per-file flags */
>
> and BITS_TO_LONGS should be used here.
>
>> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> []
>> @@ -362,7 +363,8 @@ 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;
>> + for (i = 0; i < FI_ARRAY_SIZE; i++)
>> + fi->flags[i] = 0;
>
> And this could become
>
> bitmap_zero(fi->flags, BITS_TO_LONG(FI_MAX));
>
> Is FI_ARRAY_SIZE used anywhere else?
Updated in v5, thanks.
Thanks,
>
> .
>
next prev parent reply other threads:[~2020-03-23 3:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 2:41 [PATCH v4] f2fs: fix potential .flags overflow on 32bit architecture Chao Yu
2020-03-23 2:57 ` Joe Perches
2020-03-23 3:22 ` Chao Yu [this message]
2020-03-23 3:05 ` Ondřej Jirman
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