scsi: ses: Fix possible desc_ptr out-of-bounds accesses

Sanitize possible desc_ptr out-of-bounds accesses in
ses_enclosure_data_process().

Link: https://lore.kernel.org/r/20230202162451.15346-4-thenzl@redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index 458ca7a..f8031d0 100644 (file)
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -578,15 +578,19 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
                        int max_desc_len;
 
                        if (desc_ptr) {
-                               if (desc_ptr >= buf + page7_len) {
+                               if (desc_ptr + 3 >= buf + page7_len) {
                                        desc_ptr = NULL;
                                } else {
                                        len = (desc_ptr[2] << 8) + desc_ptr[3];
                                        desc_ptr += 4;
-                                       /* Add trailing zero - pushes into
-                                        * reserved space */
-                                       desc_ptr[len] = '\0';
-                                       name = desc_ptr;
+                                       if (desc_ptr + len > buf + page7_len)
+                                               desc_ptr = NULL;
+                                       else {
+                                               /* Add trailing zero - pushes into
+                                                * reserved space */
+                                               desc_ptr[len] = '\0';
+                                               name = desc_ptr;
+                                       }
                                }
                        }
                        if (type_ptr[0] == ENCLOSURE_COMPONENT_DEVICE ||