4.4-stable review patch. If anyone has any objections, please let me know.
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From: Ben Hutchings ben.hutchings@codethink.co.uk
Extracted from commit dc503a8ad984 "bpf/verifier: track liveness for pruning".
Cc: Daniel Borkmann daniel@iogearbox.net Cc: Alexei Starovoitov ast@kernel.org Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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;