From b79e10fce4dfceddbc9adb706d7a3300df5fabe6 Mon Sep 17 00:00:00 2001
From: Markus Metzger <markus.t.metzger@intel.com>
Date: Mon, 16 Oct 2023 07:25:19 +0000
Subject: [PATCH 2/2] libipt, ptunit: avoid lto maybe-uninitialized warning

Building with GCC 13 and -flto produces

    In function 'pt_qry_get_offset',
        inlined from 'get_offset_null' at .../libipt/test/src/ptunit-block_decoder.c:164:12,
        inlined from 'main' at .../libipt/test/src/ptunit-block_decoder.c:336:2:
    .../libipt/src/pt_query_decoder.c:380:16: error: 'decoder' may be used uninitialized [-Werror=maybe-uninitialized]
      380 |         return pt_evt_get_offset(&decoder->evdec, offset);
          |                ^
    .../libipt/src/pt_event_decoder.c: In function 'main':
    .../libipt/src/pt_event_decoder.c:1541:5: note: by argument 1 of type 'const struct pt_event_decoder *' to 'pt_evt_get_offset' declared here
     1541 | int pt_evt_get_offset(const struct pt_event_decoder *decoder, uint64_t *offset)
          |     ^
    .../libipt/test/src/ptunit-block_decoder.c:157:33: note: 'decoder' declared here
      157 |         struct pt_block_decoder decoder;
          |                                 ^

Those are false positive since the decoder object isn't actually used.  In

    &decoder->evdec

we compute the address of the event decoder object within the block
decoder object.  This adds an offset defined by the type.  It does not
actually dereference the pointer to access an uninitialized decoder
object.

Initialize the test decoder to avoid those warnings.  Fixes #101.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
---
 libipt/test/src/ptunit-block_decoder.c  | 4 ++++
 libipt/test/src/ptunit-encoder.c        | 2 ++
 libipt/test/src/ptunit-insn_decoder.c   | 4 ++++
 libipt/test/src/ptunit-packet_decoder.c | 4 ++++
 4 files changed, 14 insertions(+)

diff --git a/libipt/test/src/ptunit-block_decoder.c b/libipt/test/src/ptunit-block_decoder.c
index 44249d3..d1ff288 100644
--- a/libipt/test/src/ptunit-block_decoder.c
+++ b/libipt/test/src/ptunit-block_decoder.c
@@ -158,6 +158,8 @@ static struct ptunit_result get_offset_null(void)
 	uint64_t offset;
 	int errcode;
 
+	memset(&decoder, 0, sizeof(decoder));
+
 	errcode = pt_blk_get_offset(NULL, &offset);
 	ptu_int_eq(errcode, -pte_invalid);
 
@@ -184,6 +186,8 @@ static struct ptunit_result get_sync_offset_null(void)
 	uint64_t offset;
 	int errcode;
 
+	memset(&decoder, 0, sizeof(decoder));
+
 	errcode = pt_blk_get_sync_offset(NULL, &offset);
 	ptu_int_eq(errcode, -pte_invalid);
 
diff --git a/libipt/test/src/ptunit-encoder.c b/libipt/test/src/ptunit-encoder.c
index 15d5eb4..edabe9e 100644
--- a/libipt/test/src/ptunit-encoder.c
+++ b/libipt/test/src/ptunit-encoder.c
@@ -138,6 +138,8 @@ static struct ptunit_result get_offset_null(void)
 	uint64_t offset;
 	int errcode;
 
+	memset(&encoder, 0, sizeof(encoder));
+
 	errcode = pt_enc_get_offset(NULL, &offset);
 	ptu_int_eq(errcode, -pte_invalid);
 
diff --git a/libipt/test/src/ptunit-insn_decoder.c b/libipt/test/src/ptunit-insn_decoder.c
index c8447e7..c5a057c 100644
--- a/libipt/test/src/ptunit-insn_decoder.c
+++ b/libipt/test/src/ptunit-insn_decoder.c
@@ -158,6 +158,8 @@ static struct ptunit_result get_offset_null(void)
 	uint64_t offset;
 	int errcode;
 
+	memset(&decoder, 0, sizeof(decoder));
+
 	errcode = pt_insn_get_offset(NULL, &offset);
 	ptu_int_eq(errcode, -pte_invalid);
 
@@ -184,6 +186,8 @@ static struct ptunit_result get_sync_offset_null(void)
 	uint64_t offset;
 	int errcode;
 
+	memset(&decoder, 0, sizeof(decoder));
+
 	errcode = pt_insn_get_sync_offset(NULL, &offset);
 	ptu_int_eq(errcode, -pte_invalid);
 
diff --git a/libipt/test/src/ptunit-packet_decoder.c b/libipt/test/src/ptunit-packet_decoder.c
index 39f1ede..4cb60ad 100644
--- a/libipt/test/src/ptunit-packet_decoder.c
+++ b/libipt/test/src/ptunit-packet_decoder.c
@@ -158,6 +158,8 @@ static struct ptunit_result get_offset_null(void)
 	uint64_t offset;
 	int errcode;
 
+	memset(&decoder, 0, sizeof(decoder));
+
 	errcode = pt_pkt_get_offset(NULL, &offset);
 	ptu_int_eq(errcode, -pte_invalid);
 
@@ -199,6 +201,8 @@ static struct ptunit_result get_sync_offset_null(void)
 	uint64_t offset;
 	int errcode;
 
+	memset(&decoder, 0, sizeof(decoder));
+
 	errcode = pt_pkt_get_sync_offset(NULL, &offset);
 	ptu_int_eq(errcode, -pte_invalid);
 
-- 
2.41.0