target/pscsi: Reject cross page boundary case in pscsi_map_sg

We can only have one page of data in each sg element, so we can not
cross a page boundary. Fail this case.

The 'while (len > 0 && data_len > 0) {}' loop is not necessary. The loop
can only be executed once.

Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 82e78d7..e992b27 100644 (file)
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -883,7 +883,14 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
                pr_debug("PSCSI: i: %d page: %p len: %d off: %d\n", i,
                        page, len, off);
 
-               while (len > 0 && data_len > 0) {
+               /*
+                * We only have one page of data in each sg element,
+                * we can not cross a page boundary.
+                */
+               if (off + len > PAGE_SIZE)
+                       goto fail;
+
+               if (len > 0 && data_len > 0) {
                        bytes = min_t(unsigned int, len, PAGE_SIZE - off);
                        bytes = min(bytes, data_len);
 
@@ -940,9 +947,7 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
                                bio = NULL;
                        }
 
-                       len -= bytes;
                        data_len -= bytes;
-                       off = 0;
                }
        }