From: Maxim Mikityanskiy <maxim@xxxxxxxxxxxxx>
Put calculation of the register value width into a dedicated function.
This function will also be used in a following commit.
Signed-off-by: Maxim Mikityanskiy <maxim@xxxxxxxxxxxxx>
---
kernel/bpf/verifier.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index e3eff2becd64..4cd82a7c1318 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4450,6 +4450,11 @@ static bool is_bpf_st_mem(struct bpf_insn *insn)
return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM;
}
+static int get_reg_width(struct bpf_reg_state *reg)
+{
+ return fls64(reg->umax_value);
+}
+
/* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
* stack boundary and alignment are checked in check_mem_access()
*/
@@ -4502,7 +4507,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && env->bpf_capable) {
save_register_state(env, state, spi, reg, size);
/* Break the relation on a narrowing spill. */
- if (fls64(reg->umax_value) > BITS_PER_BYTE * size)
+ if (get_reg_width(reg) > BITS_PER_BYTE * size)
state->stack[spi].spilled_ptr.id = 0;
} else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) &&
insn->imm != 0 && env->bpf_capable) {
@@ -13955,7 +13960,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
return -EACCES;
} else if (src_reg->type == SCALAR_VALUE) {
if (insn->off == 0) {
- bool is_src_reg_u32 = src_reg->umax_value <= U32_MAX;
+ bool is_src_reg_u32 = get_reg_width(src_reg) <= 32;
if (is_src_reg_u32)
assign_scalar_id_before_mov(env, src_reg);
--
2.43.0
