From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
We need to ensure that we create the mirror requests before calling
nfs_pageio_add_request_mirror() on the request we are adding.
Otherwise, we can end up with a use-after-free if the call to
nfs_pageio_add_request_mirror() triggers I/O.
Fixes: c917cfaf9bbe ("NFS: Fix up NFS I/O subrequest creation")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
fs/nfs/pagelist.c | 48 +++++++++++++++++++++++------------------------
1 file changed, 24 insertions(+), 24 deletions(-)
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 0e3f0f241d83..99eb839c5778 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -1191,38 +1191,38 @@ int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
if (desc->pg_error < 0)
goto out_failed;
- for (midx = 0; midx < desc->pg_mirror_count; midx++) {
- if (midx) {
- nfs_page_group_lock(req);
-
- /* find the last request */
- for (lastreq = req->wb_head;
- lastreq->wb_this_page != req->wb_head;
- lastreq = lastreq->wb_this_page)
- ;
-
- dupreq = nfs_create_subreq(req, lastreq,
- pgbase, offset, bytes);
-
- nfs_page_group_unlock(req);
- if (IS_ERR(dupreq)) {
- desc->pg_error = PTR_ERR(dupreq);
- goto out_failed;
- }
- } else
- dupreq = req;
+ /* Create the mirror instances first, and fire them off */
+ for (midx = 1; midx < desc->pg_mirror_count; midx++) {
+ nfs_page_group_lock(req);
+
+ /* find the last request */
+ for (lastreq = req->wb_head;
+ lastreq->wb_this_page != req->wb_head;
+ lastreq = lastreq->wb_this_page)
+ ;
+
+ dupreq = nfs_create_subreq(req, lastreq,
+ pgbase, offset, bytes);
+
+ nfs_page_group_unlock(req);
+ if (IS_ERR(dupreq)) {
+ desc->pg_error = PTR_ERR(dupreq);
+ goto out_failed;
+ }
- if (nfs_pgio_has_mirroring(desc))
- desc->pg_mirror_idx = midx;
+ desc->pg_mirror_idx = midx;
if (!nfs_pageio_add_request_mirror(desc, dupreq))
goto out_cleanup_subreq;
}
+ desc->pg_mirror_idx = 0;
+ if (!nfs_pageio_add_request_mirror(desc, req))
+ goto out_failed;
+
return 1;
out_cleanup_subreq:
- if (req != dupreq)
- nfs_pageio_cleanup_request(desc, dupreq);
+ nfs_pageio_cleanup_request(desc, dupreq);
out_failed:
nfs_pageio_error_cleanup(desc);
return 0;
--
2.25.1
