Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , Ben Hutchings Subject: [PATCH 4.9 058/101] bpf/verifier: Add spi variable to check_stack_write() Date: Thu, 6 Dec 2018 15:38:57 +0100 Message-Id: <20181206143014.935676158@linuxfoundation.org> In-Reply-To: <20181206143011.174892052@linuxfoundation.org> References: <20181206143011.174892052@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings Extracted from commit dc503a8ad984 "bpf/verifier: track liveness for pruning". Cc: Daniel Borkmann Cc: Alexei Starovoitov Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/verifier.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -543,7 +543,7 @@ static bool is_spillable_regtype(enum bp static int check_stack_write(struct bpf_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 */ @@ -558,15 +558,13 @@ static int check_stack_write(struct bpf_ } /* 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 bpf_reg_state) {}; + state->spilled_regs[spi] = (struct bpf_reg_state) {}; for (i = 0; i < size; i++) state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;