Re: [PATCH] ceph: fix potential ERR_PTR dereference in ceph_submit_write()

[nana]

 Hi  Slava
      You're correct: the fix doesn't make sense.The 
BUG_ON(IS_ERR(req))  ensures that req is a valid pointer, There is no 
code path that can skip the allocation code.

Thank you for your review.

在 2026年04月18日 01:48, Viacheslav Dubeyko 写道:
> On Fri, 2026-04-17 at 16:06 +0800, Hongling Zeng wrote:
> > Fix smatch warning:
> >   fs/ceph/addr.c:1489 ceph_submit_write() error: 'req' dereferencing possible ERR_PTR()
> >
> > Add a check to ensure req is not an ERR_PTR before calling
> > ceph_osdc_put_request().
> >
> > Fixes: 1551ec61dc55 ("ceph: improve error handling in writeback")
> > Signed-off-by: Hongling Zeng <zenghongling@xxxxxxxxxx>
> > ---
> >   fs/ceph/addr.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> > index fa4f25f99409..6091818674be 100644
> > --- a/fs/ceph/addr.c
> > +++ b/fs/ceph/addr.c
> > @@ -1468,7 +1468,8 @@ int ceph_submit_write(struct address_space *mapping,
> >   			unlock_page(page);
> >   		}
> >   
> > -		ceph_osdc_put_request(req);
> > +		if (!IS_ERR(req))
> > +			ceph_osdc_put_request(req);
> >   		return -EIO;
> >   	}
> >   
> I don't think that this fix makes sense. We create and check the request here
> [1]:
>
> 	req = ceph_osdc_new_request(&fsc->client->osdc,
> 				    &ci->i_layout, vino,
> 				    offset, &len, 0, ceph_wbc->num_ops,
> 				    CEPH_OSD_OP_WRITE, CEPH_OSD_FLAG_WRITE,
> 				    ceph_wbc->snapc, ceph_wbc->truncate_seq,
> 				    ceph_wbc->truncate_size, false);
> 	if (IS_ERR(req)) {
> 		req = ceph_osdc_new_request(&fsc->client->osdc,
> 					    &ci->i_layout, vino,
> 					    offset, &len, 0,
> 					    min(ceph_wbc->num_ops,
> 						CEPH_OSD_SLAB_OPS),
> 					    CEPH_OSD_OP_WRITE,
> 					    CEPH_OSD_FLAG_WRITE,
> 					    ceph_wbc->snapc,
> 					    ceph_wbc->truncate_seq,
> 					    ceph_wbc->truncate_size,
> 					    true);
> 		BUG_ON(IS_ERR(req));
> 	}
>
> So, it should be the valid request pointer when we called
> ceph_osdc_put_request(). Am I missing something?
>
> Thanks,
> Slava.
>
> [1] https://elixir.bootlin.com/linux/v7.0/source/fs/ceph/addr.c#L1421