delta: reject sector sizes that overflow 16-bit match length

F/2582

Author: danielinux

src/delta.c

@@ -233,6 +233,12 @@ int wb_diff_get_sector_size(void)
         fprintf(stderr, "WOLFBOOT_SECTOR_SIZE cannot be 0\n");
         exit(6);
     }
+    if (sec_sz > 0xFFFFU) {
+        fprintf(stderr,
+            "WOLFBOOT_SECTOR_SIZE (%" PRIu32 ") exceeds delta encoding limit (65535)\n",
+            sec_sz);
+        exit(6);
+    }
     if (sec_sz > (uint32_t)INT_MAX) {
         fprintf(stderr, "WOLFBOOT_SECTOR_SIZE (%" PRIu32 ") exceeds INT_MAX (%d)\n",
             sec_sz, INT_MAX);

tools/unit-tests/unit-delta.c

@@ -25,6 +25,9 @@
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
 
 #include "delta.h"
 #define WC_RSA_BLINDING
@@ -480,6 +483,36 @@ START_TEST(test_wb_patch_and_diff_multi_sector_images)
 }
 END_TEST
 
+START_TEST(test_wb_diff_get_sector_size_rejects_values_above_16bit)
+{
+    const char *saved = getenv("WOLFBOOT_SECTOR_SIZE");
+    char *saved_copy = saved ? strdup(saved) : NULL;
+    pid_t pid;
+    int status = 0;
+
+    ck_assert_int_eq(setenv("WOLFBOOT_SECTOR_SIZE", "0x20000", 1), 0);
+    pid = fork();
+    ck_assert_int_ne(pid, -1);
+
+    if (pid == 0) {
+        (void)wb_diff_get_sector_size();
+        _exit(0);
+    }
+
+    ck_assert_int_eq(waitpid(pid, &status, 0), pid);
+    ck_assert_int_eq(WIFEXITED(status), 1);
+    ck_assert_int_eq(WEXITSTATUS(status), 6);
+
+    if (saved_copy != NULL) {
+        ck_assert_int_eq(setenv("WOLFBOOT_SECTOR_SIZE", saved_copy, 1), 0);
+        free(saved_copy);
+    }
+    else {
+        ck_assert_int_eq(unsetenv("WOLFBOOT_SECTOR_SIZE"), 0);
+    }
+}
+END_TEST
+
 START_TEST(test_wb_patch_and_diff_size_changing_update)
 {
     uint8_t src_a[2048];
@@ -539,6 +572,7 @@ Suite *patch_diff_suite(void)
     tcase_add_test(tc_wolfboot_delta, test_wb_patch_and_diff_completely_different_images);
     tcase_add_test(tc_wolfboot_delta, test_wb_patch_and_diff_all_escape_images);
     tcase_add_test(tc_wolfboot_delta, test_wb_patch_and_diff_multi_sector_images);
+    tcase_add_test(tc_wolfboot_delta, test_wb_diff_get_sector_size_rejects_values_above_16bit);
     tcase_add_test(tc_wolfboot_delta, test_wb_patch_and_diff_size_changing_update);
     tcase_add_test(tc_wolfboot_delta, test_wb_patch_and_diff_single_byte_difference);
     suite_add_tcase(s, tc_wolfboot_delta);