diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b416bba3a62b..8ad819132dde 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1259,6 +1259,11 @@ static inline bool bpf_allow_ptr_leaks(void)
 	return perfmon_capable();
 }
 
+static inline bool bpf_allow_uninit_stack(void)
+{
+	return perfmon_capable();
+}
+
 static inline bool bpf_allow_ptr_to_map_access(void)
 {
 	return perfmon_capable();
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index e83ef6f6bf43..85bac3191e12 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -187,7 +187,7 @@ struct bpf_func_state {
 	 * 0 = main function, 1 = first callee.
 	 */
 	u32 frameno;
-	/* subprog number == index within subprog_stack_depth
+	/* subprog number == index within subprog_info
 	 * zero == main subprog
 	 */
 	u32 subprogno;
@@ -390,6 +390,7 @@ struct bpf_verifier_env {
 	u32 used_map_cnt;		/* number of used maps */
 	u32 id_gen;			/* used to generate unique reg IDs */
 	bool allow_ptr_leaks;
+	bool allow_uninit_stack;
 	bool allow_ptr_to_map_access;
 	bool bpf_capable;
 	bool bypass_spec_v1;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2e09e691a6be..94923c2bdd81 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2268,12 +2268,14 @@ static void save_register_state(struct bpf_func_state *state,
 		state->stack[spi].slot_type[i] = STACK_SPILL;
 }
 
-/* check_stack_read/write functions track spill/fill of registers,
+/* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
  * stack boundary and alignment are checked in check_mem_access()
  */
-static int check_stack_write(struct bpf_verifier_env *env,
-			     struct bpf_func_state *state, /* func where register points to */
-			     int off, int size, int value_regno, int insn_idx)
+static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
+				       /* stack frame we're writing to */
+				       struct bpf_func_state *state,
+				       int off, int size, int value_regno,
+				       int insn_idx)
 {
 	struct bpf_func_state *cur; /* state of the current function */
 	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
@@ -2399,9 +2401,175 @@ static int check_stack_write(struct bpf_verifier_env *env,
 	return 0;
 }
 
-static int check_stack_read(struct bpf_verifier_env *env,
-			    struct bpf_func_state *reg_state /* func where register points to */,
-			    int off, int size, int value_regno)
+/* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is
+ * known to contain a variable offset.
+ * This function checks whether the write is permitted and conservatively
+ * tracks the effects of the write, considering that each stack slot in the
+ * dynamic range is potentially written to.
+ *
+ * 'off' includes 'regno->off'.
+ * 'value_regno' can be -1, meaning that an unknown value is being written to
+ * the stack.
+ *
+ * Spilled pointers in range are not marked as written because we don't know
+ * what's going to be actually written. This means that read propagation for
+ * future reads cannot be terminated by this write.
+ *
+ * For privileged programs, uninitialized stack slots are considered
+ * initialized by this write (even though we don't know exactly what offsets
+ * are going to be written to). The idea is that we don't want the verifier to
+ * reject future reads that access slots written to through variable offsets.
+ */
+static int check_stack_write_var_off(struct bpf_verifier_env *env,
+				     /* func where register points to */
+				     struct bpf_func_state *state,
+				     int ptr_regno, int off, int size,
+				     int value_regno, int insn_idx)
+{
+	struct bpf_func_state *cur; /* state of the current function */
+	int min_off, max_off;
+	int i, err;
+	struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL;
+	bool writing_zero = false;
+	/* set if the fact that we're writing a zero is used to let any
+	 * stack slots remain STACK_ZERO
+	 */
+	bool zero_used = false;
+
+	cur = env->cur_state->frame[env->cur_state->curframe];
+	ptr_reg = &cur->regs[ptr_regno];
+	min_off = ptr_reg->smin_value + off;
+	max_off = ptr_reg->smax_value + off + size;
+	if (value_regno >= 0)
+		value_reg = &cur->regs[value_regno];
+	if (value_reg && register_is_null(value_reg))
+		writing_zero = true;
+
+	err = realloc_func_state(state, round_up(-min_off, BPF_REG_SIZE),
+				 state->acquired_refs, true);
+	if (err)
+		return err;
+
+
+	/* Variable offset writes destroy any spilled pointers in range. */
+	for (i = min_off; i < max_off; i++) {
+		u8 new_type, *stype;
+		int slot, spi;
+
+		slot = -i - 1;
+		spi = slot / BPF_REG_SIZE;
+		stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
+
+		if (!env->allow_ptr_leaks
+				&& *stype != NOT_INIT
+				&& *stype != SCALAR_VALUE) {
+			/* Reject the write if there's are spilled pointers in
+			 * range. If we didn't reject here, the ptr status
+			 * would be erased below (even though not all slots are
+			 * actually overwritten), possibly opening the door to
+			 * leaks.
+			 */
+			verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d",
+				insn_idx, i);
+			return -EINVAL;
+		}
+
+		/* Erase all spilled pointers. */
+		state->stack[spi].spilled_ptr.type = NOT_INIT;
+
+		/* Update the slot type. */
+		new_type = STACK_MISC;
+		if (writing_zero && *stype == STACK_ZERO) {
+			new_type = STACK_ZERO;
+			zero_used = true;
+		}
+		/* If the slot is STACK_INVALID, we check whether it's OK to
+		 * pretend that it will be initialized by this write. The slot
+		 * might not actually be written to, and so if we mark it as
+		 * initialized future reads might leak uninitialized memory.
+		 * For privileged programs, we will accept such reads to slots
+		 * that may or may not be written because, if we're reject
+		 * them, the error would be too confusing.
+		 */
+		if (*stype == STACK_INVALID && !env->allow_uninit_stack) {
+			verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d",
+					insn_idx, i);
+			return -EINVAL;
+		}
+		*stype = new_type;
+	}
+	if (zero_used) {
+		/* backtracking doesn't work for STACK_ZERO yet. */
+		err = mark_chain_precision(env, value_regno);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+/* When register 'dst_regno' is assigned some values from stack[min_off,
+ * max_off), we set the register's type according to the types of the
+ * respective stack slots. If all the stack values are known to be zeros, then
+ * so is the destination reg. Otherwise, the register is considered to be
+ * SCALAR. This function does not deal with register filling; the caller must
+ * ensure that all spilled registers in the stack range have been marked as
+ * read.
+ */
+static void mark_reg_stack_read(struct bpf_verifier_env *env,
+				/* func where src register points to */
+				struct bpf_func_state *ptr_state,
+				int min_off, int max_off, int dst_regno)
+{
+	struct bpf_verifier_state *vstate = env->cur_state;
+	struct bpf_func_state *state = vstate->frame[vstate->curframe];
+	int i, slot, spi;
+	u8 *stype;
+	int zeros = 0;
+
+	for (i = min_off; i < max_off; i++) {
+		slot = -i - 1;
+		spi = slot / BPF_REG_SIZE;
+		stype = ptr_state->stack[spi].slot_type;
+		if (stype[slot % BPF_REG_SIZE] != STACK_ZERO)
+			break;
+		zeros++;
+	}
+	if (zeros == max_off - min_off) {
+		/* any access_size read into register is zero extended,
+		 * so the whole register == const_zero
+		 */
+		__mark_reg_const_zero(&state->regs[dst_regno]);
+		/* backtracking doesn't support STACK_ZERO yet,
+		 * so mark it precise here, so that later
+		 * backtracking can stop here.
+		 * Backtracking may not need this if this register
+		 * doesn't participate in pointer adjustment.
+		 * Forward propagation of precise flag is not
+		 * necessary either. This mark is only to stop
+		 * backtracking. Any register that contributed
+		 * to const 0 was marked precise before spill.
+		 */
+		state->regs[dst_regno].precise = true;
+	} else {
+		/* have read misc data from the stack */
+		mark_reg_unknown(env, state->regs, dst_regno);
+	}
+	state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
+}
+
+/* Read the stack at 'off' and put the results into the register indicated by
+ * 'dst_regno'. It handles reg filling if the addressed stack slot is a
+ * spilled reg.
+ *
+ * 'dst_regno' can be -1, meaning that the read value is not going to a
+ * register.
+ *
+ * The access is assumed to be within the current stack bounds.
+ */
+static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
+				      /* func where src register points to */
+				      struct bpf_func_state *reg_state,
+				      int off, int size, int dst_regno)
 {
 	struct bpf_verifier_state *vstate = env->cur_state;
 	struct bpf_func_state *state = vstate->frame[vstate->curframe];
@@ -2409,11 +2577,6 @@ static int check_stack_read(struct bpf_verifier_env *env,
 	struct bpf_reg_state *reg;
 	u8 *stype;
 
-	if (reg_state->allocated_stack <= slot) {
-		verbose(env, "invalid read from stack off %d+0 size %d\n",
-			off, size);
-		return -EACCES;
-	}
 	stype = reg_state->stack[spi].slot_type;
 	reg = &reg_state->stack[spi].spilled_ptr;
 
@@ -2424,9 +2587,9 @@ static int check_stack_read(struct bpf_verifier_env *env,
 				verbose(env, "invalid size of register fill\n");
 				return -EACCES;
 			}
-			if (value_regno >= 0) {
-				mark_reg_unknown(env, state->regs, value_regno);
-				state->regs[value_regno].live |= REG_LIVE_WRITTEN;
+			if (dst_regno >= 0) {
+				mark_reg_unknown(env, state->regs, dst_regno);
+				state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
 			}
 			mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
 			return 0;
@@ -2438,16 +2601,16 @@ static int check_stack_read(struct bpf_verifier_env *env,
 			}
 		}
 
-		if (value_regno >= 0) {
+		if (dst_regno >= 0) {
 			/* restore register state from stack */
-			state->regs[value_regno] = *reg;
+			state->regs[dst_regno] = *reg;
 			/* mark reg as written since spilled pointer state likely
 			 * has its liveness marks cleared by is_state_visited()
 			 * which resets stack/reg liveness for state transitions
 			 */
-			state->regs[value_regno].live |= REG_LIVE_WRITTEN;
+			state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
 		} else if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
-			/* If value_regno==-1, the caller is asking us whether
+			/* If dst_regno==-1, the caller is asking us whether
 			 * it is acceptable to use this value as a SCALAR_VALUE
 			 * (e.g. for XADD).
 			 * We must not allow unprivileged callers to do that
@@ -2459,70 +2622,167 @@ static int check_stack_read(struct bpf_verifier_env *env,
 		}
 		mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
 	} else {
-		int zeros = 0;
+		u8 type;
 
 		for (i = 0; i < size; i++) {
-			if (stype[(slot - i) % BPF_REG_SIZE] == STACK_MISC)
+			type = stype[(slot - i) % BPF_REG_SIZE];
+			if (type == STACK_MISC)
 				continue;
-			if (stype[(slot - i) % BPF_REG_SIZE] == STACK_ZERO) {
-				zeros++;
+			if (type == STACK_ZERO)
 				continue;
-			}
 			verbose(env, "invalid read from stack off %d+%d size %d\n",
 				off, i, size);
 			return -EACCES;
 		}
 		mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
-		if (value_regno >= 0) {
-			if (zeros == size) {
-				/* any size read into register is zero extended,
-				 * so the whole register == const_zero
-				 */
-				__mark_reg_const_zero(&state->regs[value_regno]);
-				/* backtracking doesn't support STACK_ZERO yet,
-				 * so mark it precise here, so that later
-				 * backtracking can stop here.
-				 * Backtracking may not need this if this register
-				 * doesn't participate in pointer adjustment.
-				 * Forward propagation of precise flag is not
-				 * necessary either. This mark is only to stop
-				 * backtracking. Any register that contributed
-				 * to const 0 was marked precise before spill.
-				 */
-				state->regs[value_regno].precise = true;
-			} else {
-				/* have read misc data from the stack */
-				mark_reg_unknown(env, state->regs, value_regno);
-			}
-			state->regs[value_regno].live |= REG_LIVE_WRITTEN;
-		}
+		if (dst_regno >= 0)
+			mark_reg_stack_read(env, reg_state, off, off + size, dst_regno);
 	}
 	return 0;
 }
 
-static int check_stack_access(struct bpf_verifier_env *env,
-			      const struct bpf_reg_state *reg,
-			      int off, int size)
+enum stack_access_src {
+	ACCESS_DIRECT = 1,  /* the access is performed by an instruction */
+	ACCESS_HELPER = 2,  /* the access is performed by a helper */
+};
+
+static int check_stack_range_initialized(struct bpf_verifier_env *env,
+					 int regno, int off, int access_size,
+					 bool zero_size_allowed,
+					 enum stack_access_src type,
+					 struct bpf_call_arg_meta *meta);
+
+static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
+{
+	return cur_regs(env) + regno;
+}
+
+/* Read the stack at 'ptr_regno + off' and put the result into the register
+ * 'dst_regno'.
+ * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'),
+ * but not its variable offset.
+ * 'size' is assumed to be <= reg size and the access is assumed to be aligned.
+ *
+ * As opposed to check_stack_read_fixed_off, this function doesn't deal with
+ * filling registers (i.e. reads of spilled register cannot be detected when
+ * the offset is not fixed). We conservatively mark 'dst_regno' as containing
+ * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable
+ * offset; for a fixed offset check_stack_read_fixed_off should be used
+ * instead.
+ */
+static int check_stack_read_var_off(struct bpf_verifier_env *env,
+				    int ptr_regno, int off, int size, int dst_regno)
 {
-	/* Stack accesses must be at a fixed offset, so that we
-	 * can determine what type of data were returned. See
-	 * check_stack_read().
+	/* The state of the source register. */
+	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
+	struct bpf_func_state *ptr_state = func(env, reg);
+	int err;
+	int min_off, max_off;
+
+	/* Note that we pass a NULL meta, so raw access will not be permitted.
 	 */
-	if (!tnum_is_const(reg->var_off)) {
+	err = check_stack_range_initialized(env, ptr_regno, off, size,
+					    false, ACCESS_DIRECT, NULL);
+	if (err)
+		return err;
+
+	min_off = reg->smin_value + off;
+	max_off = reg->smax_value + off;
+	mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno);
+	return 0;
+}
+
+/* check_stack_read dispatches to check_stack_read_fixed_off or
+ * check_stack_read_var_off.
+ *
+ * The caller must ensure that the offset falls within the allocated stack
+ * bounds.
+ *
+ * 'dst_regno' is a register which will receive the value from the stack. It
+ * can be -1, meaning that the read value is not going to a register.
+ */
+static int check_stack_read(struct bpf_verifier_env *env,
+			    int ptr_regno, int off, int size,
+			    int dst_regno)
+{
+	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
+	struct bpf_func_state *state = func(env, reg);
+	int err;
+	/* Some accesses are only permitted with a static offset. */
+	bool var_off = !tnum_is_const(reg->var_off);
+
+	/* The offset is required to be static when reads don't go to a
+	 * register, in order to not leak pointers (see
+	 * check_stack_read_fixed_off).
+	 */
+	if (dst_regno < 0 && var_off) {
 		char tn_buf[48];
 
 		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
-		verbose(env, "variable stack access var_off=%s off=%d size=%d\n",
+		verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
 			tn_buf, off, size);
 		return -EACCES;
 	}
+	/* Variable offset is prohibited for unprivileged mode for simplicity
+	 * since it requires corresponding support in Spectre masking for stack
+	 * ALU. See also retrieve_ptr_limit().
+	 */
+	if (!env->bypass_spec_v1 && var_off) {
+		char tn_buf[48];
 
-	if (off >= 0 || off < -MAX_BPF_STACK) {
-		verbose(env, "invalid stack off=%d size=%d\n", off, size);
+		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
+		verbose(env, "R%d variable offset stack access prohibited for !root, var_off=%s\n",
+				ptr_regno, tn_buf);
 		return -EACCES;
 	}
 
-	return 0;
+	if (!var_off) {
+		off += reg->var_off.value;
+		err = check_stack_read_fixed_off(env, state, off, size,
+						 dst_regno);
+	} else {
+		/* Variable offset stack reads need more conservative handling
+		 * than fixed offset ones. Note that dst_regno >= 0 on this
+		 * branch.
+		 */
+		err = check_stack_read_var_off(env, ptr_regno, off, size,
+					       dst_regno);
+	}
+	return err;
+}
+
+
+/* check_stack_write dispatches to check_stack_write_fixed_off or
+ * check_stack_write_var_off.
+ *
+ * 'ptr_regno' is the register used as a pointer into the stack.
+ * 'off' includes 'ptr_regno->off', but not its variable offset (if any).
+ * 'value_regno' is the register whose value we're writing to the stack. It can
+ * be -1, meaning that we're not writing from a register.
+ *
+ * The caller must ensure that the offset falls within the maximum stack size.
+ */
+static int check_stack_write(struct bpf_verifier_env *env,
+			     int ptr_regno, int off, int size,
+			     int value_regno, int insn_idx)
+{
+	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
+	struct bpf_func_state *state = func(env, reg);
+	int err;
+
+	if (tnum_is_const(reg->var_off)) {
+		off += reg->var_off.value;
+		err = check_stack_write_fixed_off(env, state, off, size,
+						  value_regno, insn_idx);
+	} else {
+		/* Variable offset stack reads need more conservative handling
+		 * than fixed offset ones.
+		 */
+		err = check_stack_write_var_off(env, state,
+						ptr_regno, off, size,
+						value_regno, insn_idx);
+	}
+	return err;
 }
 
 static int check_map_access_type(struct bpf_verifier_env *env, u32 regno,
@@ -2851,11 +3111,6 @@ static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
 	return -EACCES;
 }
 
-static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
-{
-	return cur_regs(env) + regno;
-}
-
 static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
 {
 	return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
@@ -2974,8 +3229,8 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
 		break;
 	case PTR_TO_STACK:
 		pointer_desc = "stack ";
-		/* The stack spill tracking logic in check_stack_write()
-		 * and check_stack_read() relies on stack accesses being
+		/* The stack spill tracking logic in check_stack_write_fixed_off()
+		 * and check_stack_read_fixed_off() relies on stack accesses being
 		 * aligned.
 		 */
 		strict = true;
@@ -3393,6 +3648,91 @@ static int check_ptr_to_map_access(struct bpf_verifier_env *env,
 	return 0;
 }
 
+/* Check that the stack access at the given offset is within bounds. The
+ * maximum valid offset is -1.
+ *
+ * The minimum valid offset is -MAX_BPF_STACK for writes, and
+ * -state->allocated_stack for reads.
+ */
+static int check_stack_slot_within_bounds(int off,
+					  struct bpf_func_state *state,
+					  enum bpf_access_type t)
+{
+	int min_valid_off;
+
+	if (t == BPF_WRITE)
+		min_valid_off = -MAX_BPF_STACK;
+	else
+		min_valid_off = -state->allocated_stack;
+
+	if (off < min_valid_off || off > -1)
+		return -EACCES;
+	return 0;
+}
+
+/* Check that the stack access at 'regno + off' falls within the maximum stack
+ * bounds.
+ *
+ * 'off' includes `regno->offset`, but not its dynamic part (if any).
+ */
+static int check_stack_access_within_bounds(
+		struct bpf_verifier_env *env,
+		int regno, int off, int access_size,
+		enum stack_access_src src, enum bpf_access_type type)
+{
+	struct bpf_reg_state *regs = cur_regs(env);
+	struct bpf_reg_state *reg = regs + regno;
+	struct bpf_func_state *state = func(env, reg);
+	int min_off, max_off;
+	int err;
+	char *err_extra;
+
+	if (src == ACCESS_HELPER)
+		/* We don't know if helpers are reading or writing (or both). */
+		err_extra = " indirect access to";
+	else if (type == BPF_READ)
+		err_extra = " read from";
+	else
+		err_extra = " write to";
+
+	if (tnum_is_const(reg->var_off)) {
+		min_off = reg->var_off.value + off;
+		if (access_size > 0)
+			max_off = min_off + access_size - 1;
+		else
+			max_off = min_off;
+	} else {
+		if (reg->smax_value >= BPF_MAX_VAR_OFF ||
+		    reg->smin_value <= -BPF_MAX_VAR_OFF) {
+			verbose(env, "invalid unbounded variable-offset%s stack R%d\n",
+				err_extra, regno);
+			return -EACCES;
+		}
+		min_off = reg->smin_value + off;
+		if (access_size > 0)
+			max_off = reg->smax_value + off + access_size - 1;
+		else
+			max_off = min_off;
+	}
+
+	err = check_stack_slot_within_bounds(min_off, state, type);
+	if (!err)
+		err = check_stack_slot_within_bounds(max_off, state, type);
+
+	if (err) {
+		if (tnum_is_const(reg->var_off)) {
+			verbose(env, "invalid%s stack R%d off=%d size=%d\n",
+				err_extra, regno, off, access_size);
+		} else {
+			char tn_buf[48];
+
+			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
+			verbose(env, "invalid variable-offset%s stack R%d var_off=%s size=%d\n",
+				err_extra, regno, tn_buf, access_size);
+		}
+	}
+	return err;
+}
 
 /* check whether memory at (regno + off) is accessible for t = (read | write)
  * if t==write, value_regno is a register which value is stored into memory
@@ -3505,8 +3845,8 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 		}
 
 	} else if (reg->type == PTR_TO_STACK) {
-		off += reg->var_off.value;
-		err = check_stack_access(env, reg, off, size);
+		/* Basic bounds checks. */
+		err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t);
 		if (err)
 			return err;
 
@@ -3515,12 +3855,12 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 		if (err)
 			return err;
 
-		if (t == BPF_WRITE)
-			err = check_stack_write(env, state, off, size,
-						value_regno, insn_idx);
-		else
-			err = check_stack_read(env, state, off, size,
+		if (t == BPF_READ)
+			err = check_stack_read(env, regno, off, size,
 					       value_regno);
+		else
+			err = check_stack_write(env, regno, off, size,
+						value_regno, insn_idx);
 	} else if (reg_is_pkt_pointer(reg)) {
 		if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
 			verbose(env, "cannot write into packet\n");
@@ -3642,49 +3982,53 @@ static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_ins
 				BPF_SIZE(insn->code), BPF_WRITE, -1, true);
 }
 
-static int __check_stack_boundary(struct bpf_verifier_env *env, u32 regno,
-				  int off, int access_size,
-				  bool zero_size_allowed)
+/* When register 'regno' is used to read the stack (either directly or through
+ * a helper function) make sure that it's within stack boundary and, depending
+ * on the access type, that all elements of the stack are initialized.
+ *
+ * 'off' includes 'regno->off', but not its dynamic part (if any).
+ *
+ * All registers that have been spilled on the stack in the slots within the
+ * read offsets are marked as read.
+ */
+static int check_stack_range_initialized(
+		struct bpf_verifier_env *env, int regno, int off,
+		int access_size, bool zero_size_allowed,
+		enum stack_access_src type, struct bpf_call_arg_meta *meta)
 {
 	struct bpf_reg_state *reg = reg_state(env, regno);
+	struct bpf_func_state *state = func(env, reg);
+	int err, min_off, max_off, i, j, slot, spi;
+	char *err_extra = type == ACCESS_HELPER ? " indirect" : "";
+	enum bpf_access_type bounds_check_type;
+	/* Some accesses can write anything into the stack, others are
+	 * read-only.
+	 */
+	bool clobber = false;
 
-	if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
-	    access_size < 0 || (access_size == 0 && !zero_size_allowed)) {
-		if (tnum_is_const(reg->var_off)) {
-			verbose(env, "invalid stack type R%d off=%d access_size=%d\n",
-				regno, off, access_size);
-		} else {
-			char tn_buf[48];
-
-			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
-			verbose(env, "invalid stack type R%d var_off=%s access_size=%d\n",
-				regno, tn_buf, access_size);
-		}
+	if (access_size == 0 && !zero_size_allowed) {
+		verbose(env, "invalid zero-sized read\n");
 		return -EACCES;
 	}
-	return 0;
-}
 
-/* when register 'regno' is passed into function that will read 'access_size'
- * bytes from that pointer, make sure that it's within stack boundary
- * and all elements of stack are initialized.
- * Unlike most pointer bounds-checking functions, this one doesn't take an
- * 'off' argument, so it has to add in reg->off itself.
- */
-static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
-				int access_size, bool zero_size_allowed,
-				struct bpf_call_arg_meta *meta)
-{
-	struct bpf_reg_state *reg = reg_state(env, regno);
-	struct bpf_func_state *state = func(env, reg);
-	int err, min_off, max_off, i, j, slot, spi;
+	if (type == ACCESS_HELPER) {
+		/* The bounds checks for writes are more permissive than for
+		 * reads. However, if raw_mode is not set, we'll do extra
+		 * checks below.
+		 */
+		bounds_check_type = BPF_WRITE;
+		clobber = true;
+	} else {
+		bounds_check_type = BPF_READ;
+	}
+	err = check_stack_access_within_bounds(env, regno, off, access_size,
+					       type, bounds_check_type);
+	if (err)
+		return err;
+
 
 	if (tnum_is_const(reg->var_off)) {
-		min_off = max_off = reg->var_off.value + reg->off;
-		err = __check_stack_boundary(env, regno, min_off, access_size,
-					     zero_size_allowed);
-		if (err)
-			return err;
+		min_off = max_off = reg->var_off.value + off;
 	} else {
 		/* Variable offset is prohibited for unprivileged mode for
 		 * simplicity since it requires corresponding support in
@@ -3695,8 +4039,8 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
 			char tn_buf[48];
 
 			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
-			verbose(env, "R%d indirect variable offset stack access prohibited for !root, var_off=%s\n",
-				regno, tn_buf);
+			verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n",
+				regno, err_extra, tn_buf);
 			return -EACCES;
 		}
 		/* Only initialized buffer on stack is allowed to be accessed
@@ -3708,28 +4052,8 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
 		if (meta && meta->raw_mode)
 			meta = NULL;
 
-		if (reg->smax_value >= BPF_MAX_VAR_OFF ||
-		    reg->smax_value <= -BPF_MAX_VAR_OFF) {
-			verbose(env, "R%d unbounded indirect variable offset stack access\n",
-				regno);
-			return -EACCES;
-		}
-		min_off = reg->smin_value + reg->off;
-		max_off = reg->smax_value + reg->off;
-		err = __check_stack_boundary(env, regno, min_off, access_size,
-					     zero_size_allowed);
-		if (err) {
-			verbose(env, "R%d min value is outside of stack bound\n",
-				regno);
-			return err;
-		}
-		err = __check_stack_boundary(env, regno, max_off, access_size,
-					     zero_size_allowed);
-		if (err) {
-			verbose(env, "R%d max value is outside of stack bound\n",
-				regno);
-			return err;
-		}
+		min_off = reg->smin_value + off;
+		max_off = reg->smax_value + off;
 	}
 
 	if (meta && meta->raw_mode) {
@@ -3749,8 +4073,10 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
 		if (*stype == STACK_MISC)
 			goto mark;
 		if (*stype == STACK_ZERO) {
-			/* helper can write anything into the stack */
-			*stype = STACK_MISC;
+			if (clobber) {
+				/* helper can write anything into the stack */
+				*stype = STACK_MISC;
+			}
 			goto mark;
 		}
 
@@ -3761,22 +4087,24 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
 		if (state->stack[spi].slot_type[0] == STACK_SPILL &&
 		    (state->stack[spi].spilled_ptr.type == SCALAR_VALUE ||
 		     env->allow_ptr_leaks)) {
-			__mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
-			for (j = 0; j < BPF_REG_SIZE; j++)
-				state->stack[spi].slot_type[j] = STACK_MISC;
+			if (clobber) {
+				__mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
+				for (j = 0; j < BPF_REG_SIZE; j++)
+					state->stack[spi].slot_type[j] = STACK_MISC;
+			}
 			goto mark;
 		}
 
 err:
 		if (tnum_is_const(reg->var_off)) {
-			verbose(env, "invalid indirect read from stack off %d+%d size %d\n",
-				min_off, i - min_off, access_size);
+			verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n",
+				err_extra, regno, min_off, i - min_off, access_size);
 		} else {
 			char tn_buf[48];
 
 			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
-			verbose(env, "invalid indirect read from stack var_off %s+%d size %d\n",
-				tn_buf, i - min_off, access_size);
+			verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n",
+				err_extra, regno, tn_buf, i - min_off, access_size);
 		}
 		return -EACCES;
 mark:
@@ -3825,8 +4153,10 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 					   "rdwr",
 					   &env->prog->aux->max_rdwr_access);
 	case PTR_TO_STACK:
-		return check_stack_boundary(env, regno, access_size,
-					    zero_size_allowed, meta);
+		return check_stack_range_initialized(
+				env,
+				regno, reg->off, access_size,
+				zero_size_allowed, ACCESS_HELPER, meta);
 	default: /* scalar_value or invalid ptr */
 		/* Allow zero-byte read from NULL, regardless of pointer type */
 		if (zero_size_allowed && access_size == 0 &&
@@ -5519,6 +5849,41 @@ static int sanitize_err(struct bpf_verifier_env *env,
 	return -EACCES;
 }
 
+/* check that stack access falls within stack limits and that 'reg' doesn't
+ * have a variable offset.
+ *
+ * Variable offset is prohibited for unprivileged mode for simplicity since it
+ * requires corresponding support in Spectre masking for stack ALU.  See also
+ * retrieve_ptr_limit().
+ *
+ *
+ * 'off' includes 'reg->off'.
+ */
+static int check_stack_access_for_ptr_arithmetic(
+				struct bpf_verifier_env *env,
+				int regno,
+				const struct bpf_reg_state *reg,
+				int off)
+{
+	if (!tnum_is_const(reg->var_off)) {
+		char tn_buf[48];
+
+		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
+		verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n",
+			regno, tn_buf, off);
+		return -EACCES;
+	}
+
+	if (off >= 0 || off < -MAX_BPF_STACK) {
+		verbose(env, "R%d stack pointer arithmetic goes out of range, "
+			"prohibited for !root; off=%d\n", regno, off);
+		return -EACCES;
+	}
+
+	return 0;
+}
+
+
 /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
  * Caller should also handle BPF_MOV case separately.
  * If we return -EACCES, caller may want to try again treating pointer as a
@@ -5753,10 +6118,9 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
 				"prohibited for !root\n", dst);
 			return -EACCES;
 		} else if (dst_reg->type == PTR_TO_STACK &&
-			   check_stack_access(env, dst_reg, dst_reg->off +
-					      dst_reg->var_off.value, 1)) {
-			verbose(env, "R%d stack pointer arithmetic goes out of range, "
-				"prohibited for !root\n", dst);
+			   check_stack_access_for_ptr_arithmetic(
+				   env, dst, dst_reg, dst_reg->off +
+				   dst_reg->var_off.value)) {
 			return -EACCES;
 		}
 	}
@@ -11952,6 +12316,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 		env->strict_alignment = false;
 
 	env->allow_ptr_leaks = bpf_allow_ptr_leaks();
+	env->allow_uninit_stack = bpf_allow_uninit_stack();
 	env->allow_ptr_to_map_access = bpf_allow_ptr_to_map_access();
 	env->bypass_spec_v1 = bpf_bypass_spec_v1();
 	env->bypass_spec_v4 = bpf_bypass_spec_v4();
