Fixing undefined behavior in lib CRC (#2269)

nasa · Sep 6, 2023 · 87fa458 · 87fa458
1 parent 206f74b
commit 87fa458
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/Utils/Hash/libcrc/lib_crc.c b/Utils/Hash/libcrc/lib_crc.c
@@ -194,7 +194,9 @@ unsigned short update_crc_16( unsigned short crc, char c ) {
     if ( ! crc_tab16_init ) init_crc16_tab();
 
     tmp =  crc       ^ short_c;
-    crc = (crc >> 8) ^ crc_tab16[ tmp & 0xff ];
+    // Note: when masking by 0xff, range is limited to unsigned char
+    //       which fits within unsigned int.
+    crc = (crc >> 8) ^ crc_tab16[ (unsigned int)(tmp & 0xff) ];
 
     return crc;