X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=lttng-filter-interpreter.c;h=a9af74ad0a2c2b8697693c6a91d40e0ef97c0c85;hb=refs%2Fheads%2Fstable-2.12;hp=5bf0bd6074719ef59cf5dc8a2fe57f4cc0f5e7e7;hpb=e16c054bb621df50a1710dcd9d1d613f13ef52d2;p=lttng-modules.git

diff --git a/lttng-filter-interpreter.c b/lttng-filter-interpreter.c
index 5bf0bd60..a9af74ad 100644
--- a/lttng-filter-interpreter.c
+++ b/lttng-filter-interpreter.c
@@ -1,36 +1,21 @@
-/*
+/* SPDX-License-Identifier: MIT
+ *
  * lttng-filter-interpreter.c
  *
  * LTTng modules filter interpreter.
  *
  * Copyright (C) 2010-2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
  */
 
-#include <linux/uaccess.h>
-#include <wrapper/frame.h>
+#include <wrapper/compiler_attributes.h>
+#include <wrapper/uaccess.h>
+#include <wrapper/objtool.h>
 #include <wrapper/types.h>
 #include <linux/swab.h>
 
 #include <lttng-filter.h>
 #include <lttng-string-utils.h>
+#include <probes/lttng-probe-user.h>
 
 LTTNG_STACK_FRAME_NON_STANDARD(lttng_filter_interpret_bytecode);
 
@@ -39,7 +24,7 @@ LTTNG_STACK_FRAME_NON_STANDARD(lttng_filter_interpret_bytecode);
  * to handle user-space read.
  */
 static
-char get_char(struct estack_entry *reg, size_t offset)
+char get_char(const struct estack_entry *reg, size_t offset)
 {
 	if (unlikely(offset >= reg->u.s.seq_len))
 		return '\0';
@@ -47,7 +32,7 @@ char get_char(struct estack_entry *reg, size_t offset)
 		char c;
 
 		/* Handle invalid access as end of string. */
-		if (unlikely(!access_ok(VERIFY_READ,
+		if (unlikely(!lttng_access_ok(VERIFY_READ,
 				reg->u.s.user_str + offset,
 				sizeof(c))))
 			return '\0';
@@ -98,16 +83,14 @@ static
 int stack_star_glob_match(struct estack *stack, int top, const char *cmp_type)
 {
 	bool has_user = false;
-	mm_segment_t old_fs;
 	int result;
 	struct estack_entry *pattern_reg;
 	struct estack_entry *candidate_reg;
 
+	/* Disable the page fault handler when reading from userspace. */
 	if (estack_bx(stack, top)->u.s.user
 			|| estack_ax(stack, top)->u.s.user) {
 		has_user = true;
-		old_fs = get_fs();
-		set_fs(KERNEL_DS);
 		pagefault_disable();
 	}
 
@@ -123,10 +106,8 @@ int stack_star_glob_match(struct estack *stack, int top, const char *cmp_type)
 	/* Perform the match operation. */
 	result = !strutils_star_glob_match_char_cb(get_char_at_cb,
 		pattern_reg, get_char_at_cb, candidate_reg);
-	if (has_user) {
+	if (has_user)
 		pagefault_enable();
-		set_fs(old_fs);
-	}
 
 	return result;
 }
@@ -136,13 +117,10 @@ int stack_strcmp(struct estack *stack, int top, const char *cmp_type)
 {
 	size_t offset_bx = 0, offset_ax = 0;
 	int diff, has_user = 0;
-	mm_segment_t old_fs;
 
 	if (estack_bx(stack, top)->u.s.user
 			|| estack_ax(stack, top)->u.s.user) {
 		has_user = 1;
-		old_fs = get_fs();
-		set_fs(KERNEL_DS);
 		pagefault_disable();
 	}
 
@@ -227,10 +205,9 @@ int stack_strcmp(struct estack *stack, int top, const char *cmp_type)
 		offset_bx++;
 		offset_ax++;
 	}
-	if (has_user) {
+	if (has_user)
 		pagefault_enable();
-		set_fs(old_fs);
-	}
+
 	return diff;
 }
 
@@ -314,6 +291,8 @@ static int context_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 			ptr->u.u64 = v.s64;	/* Cast. */
 			ptr->ptr = &ptr->u.u64;
 		}
+		ptr->rev_bo = field->type.u.basic.integer.reverse_byte_order;
+		ptr->user = field->type.u.basic.integer.user;
 		break;
 	case atype_enum:
 	{
@@ -330,6 +309,8 @@ static int context_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 			ptr->u.u64 = v.s64;	/* Cast. */
 			ptr->ptr = &ptr->u.u64;
 		}
+		ptr->rev_bo = itype->reverse_byte_order;
+		ptr->user = itype->user;
 		break;
 	}
 	case atype_array:
@@ -344,6 +325,7 @@ static int context_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 		ptr->object_type = OBJECT_TYPE_STRING;
 		ctx_field->get_value(ctx_field, lttng_probe_ctx, &v);
 		ptr->ptr = v.str;
+		ptr->user = field->type.u.array.elem_type.u.basic.integer.user;
 		break;
 	case atype_sequence:
 		if (field->type.u.sequence.elem_type.atype != atype_integer) {
@@ -357,6 +339,7 @@ static int context_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 		ptr->object_type = OBJECT_TYPE_STRING;
 		ctx_field->get_value(ctx_field, lttng_probe_ctx, &v);
 		ptr->ptr = v.str;
+		ptr->user = field->type.u.sequence.elem_type.u.basic.integer.user;
 		break;
 	case atype_array_bitfield:
 		printk(KERN_WARNING "Bitfield array type is not supported.\n");
@@ -368,6 +351,7 @@ static int context_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 		ptr->object_type = OBJECT_TYPE_STRING;
 		ctx_field->get_value(ctx_field, lttng_probe_ctx, &v);
 		ptr->ptr = v.str;
+		ptr->user = field->type.u.basic.string.user;
 		break;
 	case atype_struct:
 		printk(KERN_WARNING "Structure type cannot be loaded.\n");
@@ -408,6 +392,7 @@ static int dynamic_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 			stack_top->u.ptr.ptr = ptr;
 			stack_top->u.ptr.object_type = gid->elem.type;
 			stack_top->u.ptr.rev_bo = gid->elem.rev_bo;
+			stack_top->u.ptr.user = gid->elem.user;
 			/* field is only used for types nested within variants. */
 			stack_top->u.ptr.field = NULL;
 			break;
@@ -427,6 +412,7 @@ static int dynamic_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 			stack_top->u.ptr.ptr = ptr;
 			stack_top->u.ptr.object_type = gid->elem.type;
 			stack_top->u.ptr.rev_bo = gid->elem.rev_bo;
+			stack_top->u.ptr.user = gid->elem.user;
 			/* field is only used for types nested within variants. */
 			stack_top->u.ptr.field = NULL;
 			break;
@@ -444,7 +430,8 @@ static int dynamic_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 		}
 		break;
 	case LOAD_ROOT_CONTEXT:
-	case LOAD_ROOT_APP_CONTEXT:	/* Fall-through */
+		lttng_fallthrough;
+	case LOAD_ROOT_APP_CONTEXT:
 	{
 		ret = context_get_index(lttng_probe_ctx,
 				&stack_top->u.ptr,
@@ -462,6 +449,8 @@ static int dynamic_get_index(struct lttng_probe_ctx *lttng_probe_ctx,
 		stack_top->u.ptr.type = LOAD_OBJECT;
 		/* field is only used for types nested within variants. */
 		stack_top->u.ptr.field = NULL;
+		stack_top->u.ptr.rev_bo = gid->elem.rev_bo;
+		stack_top->u.ptr.user = gid->elem.user;
 		break;
 	}
 	return 0;
@@ -488,14 +477,24 @@ static int dynamic_load_field(struct estack_entry *stack_top)
 	switch (stack_top->u.ptr.object_type) {
 	case OBJECT_TYPE_S8:
 		dbg_printk("op load field s8\n");
-		stack_top->u.v = *(int8_t *) stack_top->u.ptr.ptr;
+		if (stack_top->u.ptr.user) {
+			if (lttng_copy_from_user_check_nofault(&stack_top->u.v, (int8_t __user *) stack_top->u.ptr.ptr, sizeof(int8_t)))
+				stack_top->u.v = 0;
+		} else {
+			stack_top->u.v = *(int8_t *) stack_top->u.ptr.ptr;
+		}
 		break;
 	case OBJECT_TYPE_S16:
 	{
 		int16_t tmp;
 
 		dbg_printk("op load field s16\n");
-		tmp = *(int16_t *) stack_top->u.ptr.ptr;
+		if (stack_top->u.ptr.user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, (int16_t __user *) stack_top->u.ptr.ptr, sizeof(int16_t)))
+				tmp = 0;
+		} else {
+			tmp = *(int16_t *) stack_top->u.ptr.ptr;
+		}
 		if (stack_top->u.ptr.rev_bo)
 			__swab16s(&tmp);
 		stack_top->u.v = tmp;
@@ -506,7 +505,12 @@ static int dynamic_load_field(struct estack_entry *stack_top)
 		int32_t tmp;
 
 		dbg_printk("op load field s32\n");
-		tmp = *(int32_t *) stack_top->u.ptr.ptr;
+		if (stack_top->u.ptr.user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, (int32_t __user *) stack_top->u.ptr.ptr, sizeof(int32_t)))
+				tmp = 0;
+		} else {
+			tmp = *(int32_t *) stack_top->u.ptr.ptr;
+		}
 		if (stack_top->u.ptr.rev_bo)
 			__swab32s(&tmp);
 		stack_top->u.v = tmp;
@@ -517,7 +521,12 @@ static int dynamic_load_field(struct estack_entry *stack_top)
 		int64_t tmp;
 
 		dbg_printk("op load field s64\n");
-		tmp = *(int64_t *) stack_top->u.ptr.ptr;
+		if (stack_top->u.ptr.user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, (int64_t __user *) stack_top->u.ptr.ptr, sizeof(int64_t)))
+				tmp = 0;
+		} else {
+			tmp = *(int64_t *) stack_top->u.ptr.ptr;
+		}
 		if (stack_top->u.ptr.rev_bo)
 			__swab64s(&tmp);
 		stack_top->u.v = tmp;
@@ -525,14 +534,24 @@ static int dynamic_load_field(struct estack_entry *stack_top)
 	}
 	case OBJECT_TYPE_U8:
 		dbg_printk("op load field u8\n");
-		stack_top->u.v = *(uint8_t *) stack_top->u.ptr.ptr;
+		if (stack_top->u.ptr.user) {
+			if (lttng_copy_from_user_check_nofault(&stack_top->u.v, (uint8_t __user *) stack_top->u.ptr.ptr, sizeof(uint8_t)))
+				stack_top->u.v = 0;
+		} else {
+			stack_top->u.v = *(uint8_t *) stack_top->u.ptr.ptr;
+		}
 		break;
 	case OBJECT_TYPE_U16:
 	{
 		uint16_t tmp;
 
 		dbg_printk("op load field s16\n");
-		tmp = *(uint16_t *) stack_top->u.ptr.ptr;
+		if (stack_top->u.ptr.user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, (uint16_t __user *) stack_top->u.ptr.ptr, sizeof(uint16_t)))
+				tmp = 0;
+		} else {
+			tmp = *(uint16_t *) stack_top->u.ptr.ptr;
+		}
 		if (stack_top->u.ptr.rev_bo)
 			__swab16s(&tmp);
 		stack_top->u.v = tmp;
@@ -543,7 +562,12 @@ static int dynamic_load_field(struct estack_entry *stack_top)
 		uint32_t tmp;
 
 		dbg_printk("op load field u32\n");
-		tmp = *(uint32_t *) stack_top->u.ptr.ptr;
+		if (stack_top->u.ptr.user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, (uint32_t __user *) stack_top->u.ptr.ptr, sizeof(uint32_t)))
+				tmp = 0;
+		} else {
+			tmp = *(uint32_t *) stack_top->u.ptr.ptr;
+		}
 		if (stack_top->u.ptr.rev_bo)
 			__swab32s(&tmp);
 		stack_top->u.v = tmp;
@@ -554,7 +578,12 @@ static int dynamic_load_field(struct estack_entry *stack_top)
 		uint64_t tmp;
 
 		dbg_printk("op load field u64\n");
-		tmp = *(uint64_t *) stack_top->u.ptr.ptr;
+		if (stack_top->u.ptr.user) {
+			if (lttng_copy_from_user_check_nofault(&tmp, (uint64_t __user *) stack_top->u.ptr.ptr, sizeof(uint64_t)))
+				tmp = 0;
+		} else {
+			tmp = *(uint64_t *) stack_top->u.ptr.ptr;
+		}
 		if (stack_top->u.ptr.rev_bo)
 			__swab64s(&tmp);
 		stack_top->u.v = tmp;
@@ -562,19 +591,30 @@ static int dynamic_load_field(struct estack_entry *stack_top)
 	}
 	case OBJECT_TYPE_STRING:
 	{
-		const char *str;
+		dbg_printk("op load field string: user=%d\n", stack_top->u.ptr.user);
+		if (stack_top->u.ptr.user) {
+			const char __user *user_str = (const char __user *) stack_top->u.ptr.ptr;
 
-		dbg_printk("op load field string\n");
-		str = (const char *) stack_top->u.ptr.ptr;
-		stack_top->u.s.str = str;
-		if (unlikely(!stack_top->u.s.str)) {
-			dbg_printk("Filter warning: loading a NULL string.\n");
-			ret = -EINVAL;
-			goto end;
+			stack_top->u.s.user_str = user_str;
+			if (unlikely(!stack_top->u.s.user_str)) {
+				dbg_printk("Bytecode warning: loading a NULL user string.\n");
+				ret = -EINVAL;
+				goto end;
+			}
+			stack_top->u.s.user = 1;
+		} else {
+			const char *str = (const char *) stack_top->u.ptr.ptr;
+
+			stack_top->u.s.str = str;
+			if (unlikely(!stack_top->u.s.str)) {
+				dbg_printk("Bytecode warning: loading a NULL string.\n");
+				ret = -EINVAL;
+				goto end;
+			}
+			stack_top->u.s.user = 0;
 		}
-		stack_top->u.s.seq_len = SIZE_MAX;
-		stack_top->u.s.literal_type =
-			ESTACK_STRING_LITERAL_TYPE_NONE;
+		stack_top->u.s.seq_len = LTTNG_SIZE_MAX;
+		stack_top->u.s.literal_type = ESTACK_STRING_LITERAL_TYPE_NONE;
 		break;
 	}
 	case OBJECT_TYPE_STRING_SEQUENCE:
@@ -584,14 +624,24 @@ static int dynamic_load_field(struct estack_entry *stack_top)
 		dbg_printk("op load field string sequence\n");
 		ptr = stack_top->u.ptr.ptr;
 		stack_top->u.s.seq_len = *(unsigned long *) ptr;
-		stack_top->u.s.str = *(const char **) (ptr + sizeof(unsigned long));
-		if (unlikely(!stack_top->u.s.str)) {
-			dbg_printk("Filter warning: loading a NULL sequence.\n");
-			ret = -EINVAL;
-			goto end;
+		if (stack_top->u.ptr.user) {
+			stack_top->u.s.user_str = *(const char __user **) (ptr + sizeof(unsigned long));
+			if (unlikely(!stack_top->u.s.user_str)) {
+				dbg_printk("Bytecode warning: loading a NULL user sequence.\n");
+				ret = -EINVAL;
+				goto end;
+			}
+			stack_top->u.s.user = 1;
+		} else {
+			stack_top->u.s.str = *(const char **) (ptr + sizeof(unsigned long));
+			if (unlikely(!stack_top->u.s.str)) {
+				dbg_printk("Bytecode warning: loading a NULL sequence.\n");
+				ret = -EINVAL;
+				goto end;
+			}
+			stack_top->u.s.user = 0;
 		}
-		stack_top->u.s.literal_type =
-			ESTACK_STRING_LITERAL_TYPE_NONE;
+		stack_top->u.s.literal_type = ESTACK_STRING_LITERAL_TYPE_NONE;
 		break;
 	}
 	case OBJECT_TYPE_DYNAMIC:
@@ -618,6 +668,39 @@ end:
 	return ret;
 }
 
+#ifdef DEBUG
+
+#define DBG_USER_STR_CUTOFF 32
+
+/*
+ * In debug mode, print user string (truncated, if necessary).
+ */
+static inline
+void dbg_load_ref_user_str_printk(const struct estack_entry *user_str_reg)
+{
+	size_t pos = 0;
+	char last_char;
+	char user_str[DBG_USER_STR_CUTOFF];
+
+	pagefault_disable();
+	do {
+		last_char = get_char(user_str_reg, pos);
+		user_str[pos] = last_char;
+		pos++;
+	} while (last_char != '\0' && pos < sizeof(user_str));
+	pagefault_enable();
+
+	user_str[sizeof(user_str) - 1] = '\0';
+	dbg_printk("load field ref user string: '%s%s'\n", user_str,
+		last_char != '\0' ? "[...]" : "");
+}
+#else
+static inline
+void dbg_load_ref_user_str_printk(const struct estack_entry *user_str_reg)
+{
+}
+#endif
+
 /*
  * Return 0 (discard), or raise the 0x1 flag (log event).
  * Currently, other flags are kept for future extensions and have no
@@ -771,6 +854,8 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 		[ FILTER_OP_LOAD_FIELD_DOUBLE ] = &&LABEL_FILTER_OP_LOAD_FIELD_DOUBLE,
 
 		[ FILTER_OP_UNARY_BIT_NOT ] = &&LABEL_FILTER_OP_UNARY_BIT_NOT,
+
+		[ FILTER_OP_RETURN_S64 ] = &&LABEL_FILTER_OP_RETURN_S64,
 	};
 #endif /* #ifndef INTERPRETER_USE_SWITCH */
 
@@ -788,6 +873,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 			goto end;
 
 		OP(FILTER_OP_RETURN):
+		OP(FILTER_OP_RETURN_S64):
 			/* LTTNG_FILTER_DISCARD  or LTTNG_FILTER_RECORD_FLAG */
 			retval = !!estack_ax_v;
 			ret = 0;
@@ -990,7 +1076,12 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 		{
 			int64_t res;
 
-			res = (estack_bx_v >> estack_ax_v);
+			/* Catch undefined behavior. */
+			if (unlikely(estack_ax_v < 0 || estack_ax_v >= 64)) {
+				ret = -EINVAL;
+				goto end;
+			}
+			res = ((uint64_t) estack_bx_v >> (uint32_t) estack_ax_v);
 			estack_pop(stack, top, ax, bx);
 			estack_ax_v = res;
 			next_pc += sizeof(struct binary_op);
@@ -1000,7 +1091,12 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 		{
 			int64_t res;
 
-			res = (estack_bx_v << estack_ax_v);
+			/* Catch undefined behavior. */
+			if (unlikely(estack_ax_v < 0 || estack_ax_v >= 64)) {
+				ret = -EINVAL;
+				goto end;
+			}
+			res = ((uint64_t) estack_bx_v << (uint32_t) estack_ax_v);
 			estack_pop(stack, top, ax, bx);
 			estack_ax_v = res;
 			next_pc += sizeof(struct binary_op);
@@ -1010,7 +1106,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 		{
 			int64_t res;
 
-			res = (estack_bx_v & estack_ax_v);
+			res = ((uint64_t) estack_bx_v & (uint64_t) estack_ax_v);
 			estack_pop(stack, top, ax, bx);
 			estack_ax_v = res;
 			next_pc += sizeof(struct binary_op);
@@ -1020,7 +1116,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 		{
 			int64_t res;
 
-			res = (estack_bx_v | estack_ax_v);
+			res = ((uint64_t) estack_bx_v | (uint64_t) estack_ax_v);
 			estack_pop(stack, top, ax, bx);
 			estack_ax_v = res;
 			next_pc += sizeof(struct binary_op);
@@ -1030,7 +1126,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 		{
 			int64_t res;
 
-			res = (estack_bx_v ^ estack_ax_v);
+			res = ((uint64_t) estack_bx_v ^ (uint64_t) estack_ax_v);
 			estack_pop(stack, top, ax, bx);
 			estack_ax_v = res;
 			next_pc += sizeof(struct binary_op);
@@ -1049,7 +1145,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 
 		OP(FILTER_OP_UNARY_BIT_NOT):
 		{
-			estack_ax_v = ~estack_ax_v;
+			estack_ax_v = ~(uint64_t) estack_ax_v;
 			next_pc += sizeof(struct unary_op);
 			PO;
 		}
@@ -1325,7 +1421,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 			estack_push(stack, top, ax, bx);
 			estack_ax(stack, top)->u.s.user_str =
 				*(const char * const *) &filter_stack_data[ref->offset];
-			if (unlikely(!estack_ax(stack, top)->u.s.str)) {
+			if (unlikely(!estack_ax(stack, top)->u.s.user_str)) {
 				dbg_printk("Filter warning: loading a NULL string.\n");
 				ret = -EINVAL;
 				goto end;
@@ -1334,7 +1430,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 			estack_ax(stack, top)->u.s.literal_type =
 				ESTACK_STRING_LITERAL_TYPE_NONE;
 			estack_ax(stack, top)->u.s.user = 1;
-			dbg_printk("ref load string %s\n", estack_ax(stack, top)->u.s.str);
+			dbg_load_ref_user_str_printk(estack_ax(stack, top));
 			next_pc += sizeof(struct load_op) + sizeof(struct field_ref);
 			PO;
 		}
@@ -1352,7 +1448,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 			estack_ax(stack, top)->u.s.user_str =
 				*(const char **) (&filter_stack_data[ref->offset
 								+ sizeof(unsigned long)]);
-			if (unlikely(!estack_ax(stack, top)->u.s.str)) {
+			if (unlikely(!estack_ax(stack, top)->u.s.user_str)) {
 				dbg_printk("Filter warning: loading a NULL sequence.\n");
 				ret = -EINVAL;
 				goto end;
@@ -1546,9 +1642,10 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 				ret = -EINVAL;
 				goto end;
 			}
-			estack_ax(stack, top)->u.s.seq_len = SIZE_MAX;
+			estack_ax(stack, top)->u.s.seq_len = LTTNG_SIZE_MAX;
 			estack_ax(stack, top)->u.s.literal_type =
 				ESTACK_STRING_LITERAL_TYPE_NONE;
+			estack_ax(stack, top)->u.s.user = 0;
 			next_pc += sizeof(struct load_op);
 			PO;
 		}
@@ -1568,6 +1665,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 			}
 			estack_ax(stack, top)->u.s.literal_type =
 				ESTACK_STRING_LITERAL_TYPE_NONE;
+			estack_ax(stack, top)->u.s.user = 0;
 			next_pc += sizeof(struct load_op);
 			PO;
 		}