ia64_patch (u64 insn_addr, u64 mask, u64 val)
{
	u64 m0, m1, v0, v1, b0, b1, *b = (u64 *) (insn_addr & -16);
#	define insn_mask ((1UL << 41) - 1)
	unsigned long shift;

	b0 = b[0]; b1 = b[1];
	shift = 5 + 41 * (insn_addr % 16); /* 5 bits of template, then 3 x 41-bit instructions */
	if (shift >= 64) {
		m1 = mask << (shift - 64);
		v1 = val << (shift - 64);
	} else {
		m0 = mask << shift; m1 = mask >> (64 - shift);
		v0 = val  << shift; v1 = val >> (64 - shift);
		b[0] = (b0 & ~m0) | (v0 & m0);
	}
	b[1] = (b1 & ~m1) | (v1 & m1);
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.