libceph: check for invalid mapping

If we encounter an invalid (e.g., zeroed) mapping, return an error
and avoid a divide by zero.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

2 files changed, 36 insertions, 14 deletions

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 42119c05e82c..f7b56e23988c 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -52,7 +52,7 @@ static int op_has_extent(int op)
                 op == CEPH_OSD_OP_WRITE);
 }
 
-void ceph_calc_raw_layout(struct ceph_osd_client *osdc,
+int ceph_calc_raw_layout(struct ceph_osd_client *osdc,
                         struct ceph_file_layout *layout,
                         u64 snapid,
                         u64 off, u64 *plen, u64 *bno,
@@ -62,12 +62,15 @@ void ceph_calc_raw_layout(struct ceph_osd_client *osdc,
         struct ceph_osd_request_head *reqhead = req->r_request->front.iov_base;
         u64 orig_len = *plen;
         u64 objoff, objlen;    /* extent in object */
+        int r;
 
         reqhead->snapid = cpu_to_le64(snapid);
 
         /* object extent? */
-        ceph_calc_file_object_mapping(layout, off, plen, bno,
-                                      &objoff, &objlen);
+        r = ceph_calc_file_object_mapping(layout, off, plen, bno,
+                                          &objoff, &objlen);
+        if (r < 0)
+                return r;
         if (*plen < orig_len)
                 dout(" skipping last %llu, final file extent %llu~%llu\n",
                      orig_len - *plen, off, *plen);
@@ -83,7 +86,7 @@ void ceph_calc_raw_layout(struct ceph_osd_client *osdc,
 
         dout("calc_layout bno=%llx %llu~%llu (%d pages)\n",
              *bno, objoff, objlen, req->r_num_pages);
-
+        return 0;
 }
 EXPORT_SYMBOL(ceph_calc_raw_layout);
 
@@ -112,20 +115,25 @@ EXPORT_SYMBOL(ceph_calc_raw_layout);
  *
  * fill osd op in request message.
  */
-static void calc_layout(struct ceph_osd_client *osdc,
-                        struct ceph_vino vino,
-                        struct ceph_file_layout *layout,
-                        u64 off, u64 *plen,
-                        struct ceph_osd_request *req,
-                        struct ceph_osd_req_op *op)
+static int calc_layout(struct ceph_osd_client *osdc,
+                       struct ceph_vino vino,
+                       struct ceph_file_layout *layout,
+                       u64 off, u64 *plen,
+                       struct ceph_osd_request *req,
+                       struct ceph_osd_req_op *op)
 {
         u64 bno;
+        int r;
 
-        ceph_calc_raw_layout(osdc, layout, vino.snap, off,
-                             plen, &bno, req, op);
+        r = ceph_calc_raw_layout(osdc, layout, vino.snap, off,
+                                 plen, &bno, req, op);
+        if (r < 0)
+                return r;
 
         snprintf(req->r_oid, sizeof(req->r_oid), "%llx.%08llx", vino.ino, bno);
         req->r_oid_len = strlen(req->r_oid);
+
+        return r;
 }
 
 /*
diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 3124b71a8883..5433fb0eb3c6 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -984,7 +984,7 @@ bad:
  * for now, we write only a single su, until we can
  * pass a stride back to the caller.
  */
-void ceph_calc_file_object_mapping(struct ceph_file_layout *layout,
+int ceph_calc_file_object_mapping(struct ceph_file_layout *layout,
                                    u64 off, u64 *plen,
                                    u64 *ono,
                                    u64 *oxoff, u64 *oxlen)
@@ -998,11 +998,17 @@ void ceph_calc_file_object_mapping(struct ceph_file_layout *layout,
 
         dout("mapping %llu~%llu  osize %u fl_su %u\n", off, *plen,
              osize, su);
+        if (su == 0 || sc == 0)
+                goto invalid;
         su_per_object = osize / su;
+        if (su_per_object == 0)
+                goto invalid;
         dout("osize %u / su %u = su_per_object %u\n", osize, su,
              su_per_object);
 
-        BUG_ON((su & ~PAGE_MASK) != 0);
+        if ((su & ~PAGE_MASK) != 0)
+                goto invalid;
+
         /* bl = *off / su; */
         t = off;
         do_div(t, su);
@@ -1030,6 +1036,14 @@ void ceph_calc_file_object_mapping(struct ceph_file_layout *layout,
         *plen = *oxlen;
 
         dout(" obj extent %llu~%llu\n", *oxoff, *oxlen);
+        return 0;
+
+invalid:
+        dout(" invalid layout\n");
+        *ono = 0;
+        *oxoff = 0;
+        *oxlen = 0;
+        return -EINVAL;
 }
 EXPORT_SYMBOL(ceph_calc_file_object_mapping);