[Ocfs2-devel] [PATCH] ocfs2/o2hb: check len for bio_add_page() to avoid submitting incorrect bio

[Changwei Ge]

Hi Jun,

On 2018/3/28 17:51, Joseph Qi wrote:
> 
> 
> On 18/3/28 15:02, piaojun wrote:
>> Hi Joseph,
>>
>> On 2018/3/28 12:58, Joseph Qi wrote:
>>>
>>>
>>> On 18/3/28 11:50, piaojun wrote:
>>>> We need check len for bio_add_page() to make sure the bio has been set up
>>>> correctly, otherwise we may submit incorrect data to device.
>>>>
>>>> Signed-off-by: Jun Piao <piaojun at huawei.com>
>>>> Reviewed-by: Yiwen Jiang <jiangyiwen at huawei.com>
>>>> ---
>>>>   fs/ocfs2/cluster/heartbeat.c | 11 ++++++++++-
>>>>   1 file changed, 10 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
>>>> index ea8c551..43ad79f 100644
>>>> --- a/fs/ocfs2/cluster/heartbeat.c
>>>> +++ b/fs/ocfs2/cluster/heartbeat.c
>>>> @@ -570,7 +570,16 @@ static struct bio *o2hb_setup_one_bio(struct o2hb_region *reg,
>>>>   		     current_page, vec_len, vec_start);
>>>>
>>>>   		len = bio_add_page(bio, page, vec_len, vec_start);
>>>> -		if (len != vec_len) break;
>>>> +		if (len != vec_len) {
>>>> +			mlog(ML_ERROR, "Adding page[%d] to bio failed, "
>>>> +			     "page %p, len %d, vec_len %u, vec_start %u, "
>>>> +			     "bi_sector %llu\n", current_page, page, len,
>>>> +			     vec_len, vec_start,
>>>> +			     (unsigned long long)bio->bi_iter.bi_sector);
>>>> +			bio_put(bio);
>>>> +			bio = ERR_PTR(-EFAULT);
>>>
>>> IMO, EFAULT is not an appropriate error code here.
>>> If __bio_add_page returns 0, some are caused by bio checking failed.
>>> Also I've noticed that several other callers just use ENOMEM, so I think
>>> EINVAL or ENOMEM may be better.
>>
>> __bio_add_page has been deleted in patch c66a14d07c13, and I notice that
>> other callers always use -EFAULT or -EIO. I'm afraid we are not basing on
>> the same kernel source.
>>
> 
> Oops... Yes, I was looking an old kernel...
> EIO sounds reasonable, but I don't know why EFAULT since it means "Bad address".

I agree with Joseph that EFAULT seems unreasonable for this exception cached.
But your trick looks good to me.
After applying a more appropriate error number, please feel free to add my:
Reviewed-by: Changwei Ge <ge.changwei at h3c.com>

Thanks,
Changwei


> 
> Thanks,
> Joseph
> 
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