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>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 82e78d72fdb6..e992b27aa090 100644
--- 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;
                 }
         }