4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx> Extracted from commit dc503a8ad984 "bpf/verifier: track liveness for pruning". Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Signed-off-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/bpf/verifier.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -572,7 +572,7 @@ static bool is_spillable_regtype(enum bp static int check_stack_write(struct verifier_state *state, int off, int size, int value_regno) { - int i; + int i, spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE; /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, * so it's aligned access and [off, off + size) are within stack limits */ @@ -587,15 +587,13 @@ static int check_stack_write(struct veri } /* save register state */ - state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = - state->regs[value_regno]; + state->spilled_regs[spi] = state->regs[value_regno]; for (i = 0; i < BPF_REG_SIZE; i++) state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; } else { /* regular write of data into stack */ - state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = - (struct reg_state) {}; + state->spilled_regs[spi] = (struct reg_state) {}; for (i = 0; i < size; i++) state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;