From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
commit f528819334881fd622fdadeddb3f7edaed8b7c9b upstream.
Add a small sanitize_needed() helper function and move sanitize_val_alu()
out of the main opcode switch. In upcoming work, we'll move sanitize_ptr_alu()
as well out of its opcode switch so this helps to streamline both.
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Reviewed-by: John Fastabend <john.fastabend@xxxxxxxxx>
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
[fllinden@xxxxxxxxxx: backported to 4.14]
Signed-off-by: Frank van der Linden <fllinden@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/bpf/verifier.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2110,6 +2110,11 @@ static int sanitize_val_alu(struct bpf_v
return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
}
+static bool sanitize_needed(u8 opcode)
+{
+ return opcode == BPF_ADD || opcode == BPF_SUB;
+}
+
static int sanitize_ptr_alu(struct bpf_verifier_env *env,
struct bpf_insn *insn,
const struct bpf_reg_state *ptr_reg,
@@ -2510,11 +2515,14 @@ static int adjust_scalar_min_max_vals(st
return 0;
}
- switch (opcode) {
- case BPF_ADD:
+ if (sanitize_needed(opcode)) {
ret = sanitize_val_alu(env, insn);
if (ret < 0)
return sanitize_err(env, insn, ret, NULL, NULL);
+ }
+
+ switch (opcode) {
+ case BPF_ADD:
if (signed_add_overflows(dst_reg->smin_value, smin_val) ||
signed_add_overflows(dst_reg->smax_value, smax_val)) {
dst_reg->smin_value = S64_MIN;
@@ -2534,9 +2542,6 @@ static int adjust_scalar_min_max_vals(st
dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
break;
case BPF_SUB:
- ret = sanitize_val_alu(env, insn);
- if (ret < 0)
- return sanitize_err(env, insn, ret, NULL, NULL);
if (signed_sub_overflows(dst_reg->smin_value, smax_val) ||
signed_sub_overflows(dst_reg->smax_value, smin_val)) {
/* Overflow possible, we know nothing */
