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Message-ID: <20d02767-6e14-c04f-4fcf-11ed2cbd63a2@linux.alibaba.com>
Date: Mon, 5 Aug 2019 10:38:55 +0800
From: Changwei Ge <chge@...ux.alibaba.com>
To: Joseph Qi <joseph.qi@...ux.alibaba.com>,
Jia-Ju Bai <baijiaju1990@...il.com>, mark@...heh.com,
jlbec@...lplan.org
Cc: linux-kernel@...r.kernel.org, ocfs2-devel@....oracle.com,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [Ocfs2-devel] [PATCH 2/3] fs: ocfs2: Fix a possible null-pointer
dereference in ocfs2_write_end_nolock()
Hi Jia-ju,
Could you please point out how ->w_handle can be NULL if we are changing
disk inode?
I just checked the ocfs2 code but can't find any clue ...
In my opinion, it's impossible to change disk inode without an existed
journal transaction. If truly so, it's a another problem.
Thanks,
Changwei
On 2019/7/26 5:38 下午, Joseph Qi wrote:
>
> On 19/7/26 11:37, Jia-Ju Bai wrote:
>> In ocfs2_write_end_nolock(), there are an if statement on lines 1976,
>> 2047 and 2058, to check whether handle is NULL:
>> if (handle)
>>
>> When handle is NULL, it is used on line 2045:
>> ocfs2_update_inode_fsync_trans(handle, inode, 1);
>> oi->i_sync_tid = handle->h_transaction->t_tid;
>>
>> Thus, a possible null-pointer dereference may occur.
>>
>> To fix this bug, handle is checked before calling
>> ocfs2_update_inode_fsync_trans().
>>
>> This bug is found by a static analysis tool STCheck written by us.
>>
>> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
> Looks good.
> Reviewed-by: Joseph Qi <joseph.qi@...ux.alibaba.com>
>
>> ---
>> fs/ocfs2/aops.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
>> index a4c905d6b575..5473bd99043e 100644
>> --- a/fs/ocfs2/aops.c
>> +++ b/fs/ocfs2/aops.c
>> @@ -2042,7 +2042,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
>> inode->i_mtime = inode->i_ctime = current_time(inode);
>> di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
>> di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
>> - ocfs2_update_inode_fsync_trans(handle, inode, 1);
>> + if (handle)
>> + ocfs2_update_inode_fsync_trans(handle, inode, 1);
>> }
>> if (handle)
>> ocfs2_journal_dirty(handle, wc->w_di_bh);
>>
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