diff options
| author | Juergen Gross <jgross@suse.com> | 2021-11-29 08:45:38 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-01 09:23:35 +0100 |
| commit | 6392f51a9d2ec305da31f1c348d895b876306018 (patch) | |
| tree | c833831d8249f4258d66421046c3dc69d361f453 | |
| parent | ce011335cb426b3935e41d5ae4c0ba7934237341 (diff) | |
xen/blkfront: don't take local copy of a request from the ring page
commit 8f5a695d99000fc3aa73934d7ced33cfc64dcdab upstream.
In order to avoid a malicious backend being able to influence the local
copy of a request build the request locally first and then copy it to
the ring page instead of doing it the other way round as today.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Link: https://lore.kernel.org/r/20210730103854.12681-3-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/block/xen-blkfront.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index ce0f314817c9..d24d3d7f5b52 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -536,7 +536,7 @@ static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, rinfo->shadow[id].status = REQ_WAITING; rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID; - (*ring_req)->u.rw.id = id; + rinfo->shadow[id].req.u.rw.id = id; return id; } @@ -544,11 +544,12 @@ static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo) { struct blkfront_info *info = rinfo->dev_info; - struct blkif_request *ring_req; + struct blkif_request *ring_req, *final_ring_req; unsigned long id; /* Fill out a communications ring structure. */ - id = blkif_ring_get_request(rinfo, req, &ring_req); + id = blkif_ring_get_request(rinfo, req, &final_ring_req); + ring_req = &rinfo->shadow[id].req; ring_req->operation = BLKIF_OP_DISCARD; ring_req->u.discard.nr_sectors = blk_rq_sectors(req); @@ -559,8 +560,8 @@ static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_inf else ring_req->u.discard.flag = 0; - /* Keep a private copy so we can reissue requests when recovering. */ - rinfo->shadow[id].req = *ring_req; + /* Copy the request to the ring page. */ + *final_ring_req = *ring_req; return 0; } @@ -693,6 +694,7 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri { struct blkfront_info *info = rinfo->dev_info; struct blkif_request *ring_req, *extra_ring_req = NULL; + struct blkif_request *final_ring_req, *final_extra_ring_req = NULL; unsigned long id, extra_id = NO_ASSOCIATED_ID; bool require_extra_req = false; int i; @@ -737,7 +739,8 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri } /* Fill out a communications ring structure. */ - id = blkif_ring_get_request(rinfo, req, &ring_req); + id = blkif_ring_get_request(rinfo, req, &final_ring_req); + ring_req = &rinfo->shadow[id].req; num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg); num_grant = 0; @@ -788,7 +791,9 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri ring_req->u.rw.nr_segments = num_grant; if (unlikely(require_extra_req)) { extra_id = blkif_ring_get_request(rinfo, req, - &extra_ring_req); + &final_extra_ring_req); + extra_ring_req = &rinfo->shadow[extra_id].req; + /* * Only the first request contains the scatter-gather * list. @@ -830,10 +835,10 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri if (setup.segments) kunmap_atomic(setup.segments); - /* Keep a private copy so we can reissue requests when recovering. */ - rinfo->shadow[id].req = *ring_req; + /* Copy request(s) to the ring page. */ + *final_ring_req = *ring_req; if (unlikely(require_extra_req)) - rinfo->shadow[extra_id].req = *extra_ring_req; + *final_extra_ring_req = *extra_ring_req; if (new_persistent_gnts) gnttab_free_grant_references(setup.gref_head); |