commit 9c25fa76e5772390f1b7d4b0cc63233e6291012f
author Fabio Utzig <utzig@apache.org> Tue Dec 12 14:57:20 2017 -0200
committer David Brown <davidb@davidb.org> Thu Jan 04 10:35:26 2018 -0700
tree c757d48a4b38010fe6c9d74a26884f1dca236577
parent 539860453c23b1d9323f77b69b1bbb2e692585f3

Avoid using uninitialized memory in split go

Since boot_read_image_headers only failed when reading headers from
both Slots failed, it could happen that even with a failure reading
Slot 1, this data would still be used by split booting. Now when
reading image headers an extra parameter allows the caller to ask
for failure when any slot read failed.

JIRA: MCUB-56
Signed-off-by: Fabio Utzig <utzig@apache.org>

boot/bootutil/src/loader.c

diff --git a/boot/bootutil/src/loader.c b/boot/bootutil/src/loader.c
index 75494f6..ab8ac7b 100644
--- a/boot/bootutil/src/loader.c
+++ b/boot/bootutil/src/loader.c
@@ -285,7 +285,7 @@
 }
 
 static int
-boot_read_image_headers(void)
+boot_read_image_headers(bool require_all)
 {
     int rc;
     int i;
@@ -293,11 +293,13 @@
     for (i = 0; i < BOOT_NUM_SLOTS; i++) {
         rc = boot_read_image_header(i, boot_img_hdr(&boot_data, i));
         if (rc != 0) {
-            /* If at least the first slot's header was read successfully, then
-             * the boot loader can attempt a boot.  Failure to read any headers
-             * is a fatal error.
+            /* If `require_all` is set, fail on any single fail, otherwise
+             * if at least the first slot's header was read successfully,
+             * then the boot loader can attempt a boot.
+             *
+             * Failure to read any headers is a fatal error.
              */
-            if (i > 0) {
+            if (i > 0 && !require_all) {
                 return 0;
             } else {
                 return rc;
@@ -1338,7 +1340,7 @@
     }
 
     /* Attempt to read an image header from each slot. */
-    rc = boot_read_image_headers();
+    rc = boot_read_image_headers(false);
     if (rc != 0) {
         goto out;
     }
@@ -1409,7 +1411,7 @@
     }
 
     if (reload_headers) {
-        rc = boot_read_image_headers();
+        rc = boot_read_image_headers(false);
         if (rc != 0) {
             goto out;
         }
@@ -1485,7 +1487,7 @@
         goto done;
     }
 
-    rc = boot_read_image_headers();
+    rc = boot_read_image_headers(true);
     if (rc != 0) {
         goto done;
     }