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

From: Yan, Zheng
Date: Mon Oct 10 2016 - 09:12:04 EST



> 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>

> 2.5.0
>