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Bug #13075

String#unpack with block / String#unpack1 exposes uninitialized memory

Added by rhenium (Kazuki Yamaguchi) over 3 years ago. Updated about 3 years ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Target version:
-
[ruby-core:78841]

Description

A problematic code looks like (in pack.c, pack_unpack_internal()):

          case 'b':
            {
                VALUE bitstr;
                char *t;
                int bits;
                long i;

                if (p[-1] == '*' || len > (send - s) * 8)
                    len = (send - s) * 8;
                bits = 0;
                UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
                t = RSTRING_PTR(bitstr);
                for (i=0; i<len; i++) {
                    if (i & 7) bits >>= 1;
                    else bits = (unsigned char)*s++;
                    *t++ = (bits & 1) ? '1' : '0';
                }
            }
            break;

UNPACK_PUSH() immediately yields the value (String#unpack with block) or returns to the caller (String#unpack1), but the content bytes are not initialized at the time.

This bug dates back to r11175 (Ruby 1.9.0).

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