fix a rare i2s illegal memory access
MODIFY
src/afl-fuzz-redqueen.c
src/afl-fuzz-redqueen.c
@@ -808,39 +808,84 @@ static u8 cmp_extend_encoding(afl_state_t *afl, struct cmp_header *h,
// Try to identify transform magic
if (pattern != o_pattern && repl == changed_val && attr <= IS_EQUAL) {
- u64 *ptr = (u64 *)&buf[idx];
- u64 *o_ptr = (u64 *)&orig_buf[idx];
u64 b_val, o_b_val, mask;
+ u8 bytes;
switch (SHAPE_BYTES(h->shape)) {
case 0:
case 1:
- b_val = (u64)(*ptr % 0x100);
+ bytes = 1;
+ break;
+ case 2:
+ bytes = 2;
+ break;
+ case 3:
+ case 4:
+ bytes = 4;
+ break;
+ default:
+ bytes = 8;
+
+ }
+
+ // necessary for preventing heap access overflow
+ bytes = MIN(bytes, len - idx);
+
+ switch (bytes) {
+
+ case 0: // cannot happen
+ b_val = o_b_val = mask = 0; // keep the linters happy
+ break;
+ case 1: {
+
+ u8 *ptr = (u8 *)&buf[idx];
+ u8 *o_ptr = (u8 *)&orig_buf[idx];
+ b_val = (u64)(*ptr);
o_b_val = (u64)(*o_ptr % 0x100);
mask = 0xff;
break;
+
+ }
+
case 2:
- case 3:
- b_val = (u64)(*ptr % 0x10000);
- o_b_val = (u64)(*o_ptr % 0x10000);
+ case 3: {
+
+ u16 *ptr = (u16 *)&buf[idx];
+ u16 *o_ptr = (u16 *)&orig_buf[idx];
+ b_val = (u64)(*ptr);
+ o_b_val = (u64)(*o_ptr);
mask = 0xffff;
break;
+
+ }
+
case 4:
case 5:
case 6:
- case 7:
- b_val = (u64)(*ptr % 0x100000000);
- o_b_val = (u64)(*o_ptr % 0x100000000);
+ case 7: {
+
+ u32 *ptr = (u32 *)&buf[idx];
+ u32 *o_ptr = (u32 *)&orig_buf[idx];
+ b_val = (u64)(*ptr);
+ o_b_val = (u64)(*o_ptr);
mask = 0xffffffff;
break;
- default:
- b_val = *ptr;
- o_b_val = *o_ptr;
+
+ }
+
+ default: {
+
+ u64 *ptr = (u64 *)&buf[idx];
+ u64 *o_ptr = (u64 *)&orig_buf[idx];
+ b_val = (u64)(*ptr);
+ o_b_val = (u64)(*o_ptr);
mask = 0xffffffffffffffff;
}
+ }
+
// test for arithmetic, eg. "if ((user_val - 0x1111) == 0x1234) ..."
s64 diff = pattern - b_val;
s64 o_diff = o_pattern - o_b_val;

fix a rare i2s illegal memory access