1 files changed, 123 insertions, 52 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 11528bdaa9dc..187ea0cfbcca 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -201,8 +201,7 @@ struct bpf_call_arg_meta {
 	bool pkt_access;
 	int regno;
 	int access_size;
-	s64 msize_smax_value;
-	u64 msize_umax_value;
+	u64 msize_max_value;
 	int ref_obj_id;
 	int func_id;
 };
@@ -2657,8 +2656,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
 		/* remember the mem_size which may be used later
 		 * to refine return values.
 		 */
-		meta->msize_smax_value = reg->smax_value;
-		meta->msize_umax_value = reg->umax_value;
+		meta->msize_max_value = reg->umax_value;
 
 		/* The register is SCALAR_VALUE; the access check
 		 * happens using its boundaries.
@@ -3141,21 +3139,44 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
 	return 0;
 }
 
-static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type,
-				   int func_id,
-				   struct bpf_call_arg_meta *meta)
+static int do_refine_retval_range(struct bpf_verifier_env *env,
+				  struct bpf_reg_state *regs, int ret_type,
+				  int func_id, struct bpf_call_arg_meta *meta)
 {
 	struct bpf_reg_state *ret_reg = &regs[BPF_REG_0];
+	struct bpf_reg_state tmp_reg = *ret_reg;
+	bool ret;
 
 	if (ret_type != RET_INTEGER ||
 	    (func_id != BPF_FUNC_get_stack &&
 	     func_id != BPF_FUNC_probe_read_str))
-		return;
+		return 0;
+
+	/* Error case where ret is in interval [S32MIN, -1]. */
+	ret_reg->smin_value = S32_MIN;
+	ret_reg->smax_value = -1;
+
+	__reg_deduce_bounds(ret_reg);
+	__reg_bound_offset(ret_reg);
+	__update_reg_bounds(ret_reg);
+
+	ret = push_stack(env, env->insn_idx + 1, env->insn_idx, false);
+	if (!ret)
+		return -EFAULT;
+
+	*ret_reg = tmp_reg;
+
+	/* Success case where ret is in range [0, msize_max_value]. */
+	ret_reg->smin_value = 0;
+	ret_reg->smax_value = meta->msize_max_value;
+	ret_reg->umin_value = ret_reg->smin_value;
+	ret_reg->umax_value = ret_reg->smax_value;
 
-	ret_reg->smax_value = meta->msize_smax_value;
-	ret_reg->umax_value = meta->msize_umax_value;
 	__reg_deduce_bounds(ret_reg);
 	__reg_bound_offset(ret_reg);
+	__update_reg_bounds(ret_reg);
+
+	return 0;
 }
 
 static int
@@ -3384,7 +3405,9 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 		regs[BPF_REG_0].ref_obj_id = id;
 	}
 
-	do_refine_retval_range(regs, fn->ret_type, func_id, &meta);
+	err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta);
+	if (err)
+		return err;
 
 	err = check_map_func_compatibility(env, meta.map_ptr, func_id);
 	if (err)
@@ -4084,9 +4107,16 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
 		/* Upon reaching here, src_known is true and
 		 * umax_val is equal to umin_val.
 		 */
-		dst_reg->smin_value >>= umin_val;
-		dst_reg->smax_value >>= umin_val;
-		dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val);
+		if (insn_bitness == 32) {
+			dst_reg->smin_value = (u32)(((s32)dst_reg->smin_value) >> umin_val);
+			dst_reg->smax_value = (u32)(((s32)dst_reg->smax_value) >> umin_val);
+		} else {
+			dst_reg->smin_value >>= umin_val;
+			dst_reg->smax_value >>= umin_val;
+		}
+
+		dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val,
+						insn_bitness);
 
 		/* blow away the dst_reg umin_value/umax_value and rely on
 		 * dst_reg var_off to refine the result.
@@ -4580,6 +4610,70 @@ static bool cmp_val_with_extended_s64(s64 sval, struct bpf_reg_state *reg)
 		reg->smax_value <= 0 && reg->smin_value >= S32_MIN);
 }
 
+/* Constrain the possible values of @reg with unsigned upper bound @bound.
+ * If @is_exclusive, @bound is an exclusive limit, otherwise it is inclusive.
+ * If @is_jmp32, @bound is a 32-bit value that only constrains the low 32 bits
+ * of @reg.
+ */
+static void set_upper_bound(struct bpf_reg_state *reg, u64 bound, bool is_jmp32,
+			    bool is_exclusive)
+{
+	if (is_exclusive) {
+		/* There are no values for `reg` that make `reg<0` true. */
+		if (bound == 0)
+			return;
+		bound--;
+	}
+	if (is_jmp32) {
+		/* Constrain the register's value in the tnum representation.
+		 * For 64-bit comparisons this happens later in
+		 * __reg_bound_offset(), but for 32-bit comparisons, we can be
+		 * more precise than what can be derived from the updated
+		 * numeric bounds.
+		 */
+		struct tnum t = tnum_range(0, bound);
+
+		t.mask |= ~0xffffffffULL; /* upper half is unknown */
+		reg->var_off = tnum_intersect(reg->var_off, t);
+
+		/* Compute the 64-bit bound from the 32-bit bound. */
+		bound += gen_hi_max(reg->var_off);
+	}
+	reg->umax_value = min(reg->umax_value, bound);
+}
+
+/* Constrain the possible values of @reg with unsigned lower bound @bound.
+ * If @is_exclusive, @bound is an exclusive limit, otherwise it is inclusive.
+ * If @is_jmp32, @bound is a 32-bit value that only constrains the low 32 bits
+ * of @reg.
+ */
+static void set_lower_bound(struct bpf_reg_state *reg, u64 bound, bool is_jmp32,
+			    bool is_exclusive)
+{
+	if (is_exclusive) {
+		/* There are no values for `reg` that make `reg>MAX` true. */
+		if (bound == (is_jmp32 ? U32_MAX : U64_MAX))
+			return;
+		bound++;
+	}
+	if (is_jmp32) {
+		/* Constrain the register's value in the tnum representation.
+		 * For 64-bit comparisons this happens later in
+		 * __reg_bound_offset(), but for 32-bit comparisons, we can be
+		 * more precise than what can be derived from the updated
+		 * numeric bounds.
+		 */
+		struct tnum t = tnum_range(bound, U32_MAX);
+
+		t.mask |= ~0xffffffffULL; /* upper half is unknown */
+		reg->var_off = tnum_intersect(reg->var_off, t);
+
+		/* Compute the 64-bit bound from the 32-bit bound. */
+		bound += gen_hi_min(reg->var_off);
+	}
+	reg->umin_value = max(reg->umin_value, bound);
+}
+
 /* Adjusts the register min/max values in the case that the dst_reg is the
  * variable register that we are working on, and src_reg is a constant or we're
  * simply doing a BPF_K check.
@@ -4635,15 +4729,8 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg,
 	case BPF_JGE:
 	case BPF_JGT:
 	{
-		u64 false_umax = opcode == BPF_JGT ? val    : val - 1;
-		u64 true_umin = opcode == BPF_JGT ? val + 1 : val;
-
-		if (is_jmp32) {
-			false_umax += gen_hi_max(false_reg->var_off);
-			true_umin += gen_hi_min(true_reg->var_off);
-		}
-		false_reg->umax_value = min(false_reg->umax_value, false_umax);
-		true_reg->umin_value = max(true_reg->umin_value, true_umin);
+		set_upper_bound(false_reg, val, is_jmp32, opcode == BPF_JGE);
+		set_lower_bound(true_reg, val, is_jmp32, opcode == BPF_JGT);
 		break;
 	}
 	case BPF_JSGE:
@@ -4664,15 +4751,8 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg,
 	case BPF_JLE:
 	case BPF_JLT:
 	{
-		u64 false_umin = opcode == BPF_JLT ? val    : val + 1;
-		u64 true_umax = opcode == BPF_JLT ? val - 1 : val;
-
-		if (is_jmp32) {
-			false_umin += gen_hi_min(false_reg->var_off);
-			true_umax += gen_hi_max(true_reg->var_off);
-		}
-		false_reg->umin_value = max(false_reg->umin_value, false_umin);
-		true_reg->umax_value = min(true_reg->umax_value, true_umax);
+		set_lower_bound(false_reg, val, is_jmp32, opcode == BPF_JLE);
+		set_upper_bound(true_reg, val, is_jmp32, opcode == BPF_JLT);
 		break;
 	}
 	case BPF_JSLE:
@@ -4747,15 +4827,8 @@ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
 	case BPF_JGE:
 	case BPF_JGT:
 	{
-		u64 false_umin = opcode == BPF_JGT ? val    : val + 1;
-		u64 true_umax = opcode == BPF_JGT ? val - 1 : val;
-
-		if (is_jmp32) {
-			false_umin += gen_hi_min(false_reg->var_off);
-			true_umax += gen_hi_max(true_reg->var_off);
-		}
-		false_reg->umin_value = max(false_reg->umin_value, false_umin);
-		true_reg->umax_value = min(true_reg->umax_value, true_umax);
+		set_lower_bound(false_reg, val, is_jmp32, opcode == BPF_JGE);
+		set_upper_bound(true_reg, val, is_jmp32, opcode == BPF_JGT);
 		break;
 	}
 	case BPF_JSGE:
@@ -4773,15 +4846,8 @@ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
 	case BPF_JLE:
 	case BPF_JLT:
 	{
-		u64 false_umax = opcode == BPF_JLT ? val    : val - 1;
-		u64 true_umin = opcode == BPF_JLT ? val + 1 : val;
-
-		if (is_jmp32) {
-			false_umax += gen_hi_max(false_reg->var_off);
-			true_umin += gen_hi_min(true_reg->var_off);
-		}
-		false_reg->umax_value = min(false_reg->umax_value, false_umax);
-		true_reg->umin_value = max(true_reg->umin_value, true_umin);
+		set_upper_bound(false_reg, val, is_jmp32, opcode == BPF_JLE);
+		set_lower_bound(true_reg, val, is_jmp32, opcode == BPF_JLT);
 		break;
 	}
 	case BPF_JSLE:
@@ -5268,6 +5334,7 @@ static bool may_access_skb(enum bpf_prog_type type)
 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 {
 	struct bpf_reg_state *regs = cur_regs(env);
+	static const int ctx_reg = BPF_REG_6;
 	u8 mode = BPF_MODE(insn->code);
 	int i, err;
 
@@ -5301,7 +5368,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 	}
 
 	/* check whether implicit source operand (register R6) is readable */
-	err = check_reg_arg(env, BPF_REG_6, SRC_OP);
+	err = check_reg_arg(env, ctx_reg, SRC_OP);
 	if (err)
 		return err;
 
@@ -5320,7 +5387,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 		return -EINVAL;
 	}
 
-	if (regs[BPF_REG_6].type != PTR_TO_CTX) {
+	if (regs[ctx_reg].type != PTR_TO_CTX) {
 		verbose(env,
 			"at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
 		return -EINVAL;
@@ -5333,6 +5400,10 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 			return err;
 	}
 
+	err = check_ctx_reg(env, &regs[ctx_reg], ctx_reg);
+	if (err < 0)
+		return err;
+
 	/* reset caller saved regs to unreadable */
 	for (i = 0; i < CALLER_SAVED_REGS; i++) {
 		mark_reg_not_init(env, regs, caller_saved[i]);