bpf: do not hash uninitialized bpf memory

Subtle little bug. struct bpf_instr looks like this in memory:

struct bpf_instr {
	uint16_t                   op;                   /*     0     2 */
	/* XXX 2 bytes hole */
	struct bpf_jump            jt;                   /*     4     8 */
	struct bpf_jump            jf;                   /*    12     8 */
	uint32_t                   k;                    /*    20     4 */
};

We have the _BPF_INSTR macro which fills in the instruction field by field.
The problem with filling it in field by field is that the 2 byte hole is
never initialized and can contain random stack garbage.  This whole struct
is then memcpy'd into the state from _blk_append.  Then the whole struct is
hashed.  But now the hash contains the 2 bytes of random crap which wasn't
initialized.  Fix this by always zero-ing the whole struct in _BPF_INSTR.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>

0 files changed, 0 insertions, 0 deletions