Re: [PATCHv2] ceph: Fix error handling in ceph_read_iter

From: Nikolay Borisov
Date: Mon Oct 10 2016 - 09:29:39 EST




On 10/10/2016 04:11 PM, Yan, Zheng wrote:
>
>> On 10 Oct 2016, at 20:56, Nikolay Borisov <kernel@xxxxxxxx> wrote:
>>
>> In case __ceph_do_getattr returns an error and the retry_op in
>> ceph_read_iter is not READ_INLINE, then it's possible to invoke
>> __free_page on a page which is NULL, this naturally leads to a crash.
>> This can happen when, for example, a process waiting on a MDS reply
>> receives sigterm.
>>
>> Fix this by explicitly checking whether the page is set or not.
>>
>> Signed-off-by: Nikolay Borisov <kernel@xxxxxxxx>
>> Link: http://www.spinics.net/lists/ceph-users/msg31592.html
>> ---
>>
>> Inverted the condition, so resending with correct condition
>> this time.
>>
>> fs/ceph/file.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
>> index 3c68e6aee2f0..7413313ae6c8 100644
>> --- a/fs/ceph/file.c
>> +++ b/fs/ceph/file.c
>> @@ -929,7 +929,8 @@ again:
>> statret = __ceph_do_getattr(inode, page,
>> CEPH_STAT_CAP_INLINE_DATA, !!page);
>> if (statret < 0) {
>> - __free_page(page);
>> + if (page)
>> + __free_page(page);
>> if (statret == -ENODATA) {
>> BUG_ON(retry_op != READ_INLINE);
>> goto again;
>> â
> Reviewed-by: Yan, Zheng <zyan@xxxxxxxxxx>

I believe this needs to also be tagged as stable. To whomever is going
to merge it: can you please do that?


>
>> 2.5.0
>>
>