Fix: do not resolve debug info on build id mismatch

include/babeltrace/bin-info.h

@@ -62,6 +62,8 @@ struct bin_info {
 	int dwarf_fd;
 	/* Denotes whether the executable is position independent code. */
 	bool is_pic:1;
+	/* Denotes whether the build id in the trace matches to one on disk. */
+	bool file_build_id_matches:1;
 	/*
 	 * Denotes whether the executable only has ELF symbols and no
 	 * DWARF info.

lib/bin-info.c

@@ -49,6 +49,7 @@
  * character).
  */
 #define ADDR_STR_LEN 20
+#define BUILD_ID_NOTE_NAME "GNU"
 
 BT_HIDDEN
 int bin_info_init(void)
@@ -94,6 +95,9 @@ struct bin_info *bin_info_create(const char *path, uint64_t low_addr,
 	bin->memsz = memsz;
 	bin->low_addr = low_addr;
 	bin->high_addr = bin->low_addr + bin->memsz;
+	bin->build_id = NULL;
+	bin->build_id_len = 0;
+	bin->file_build_id_matches = false;
 
 	return bin;
 
@@ -124,37 +128,6 @@ void bin_info_destroy(struct bin_info *bin)
 	g_free(bin);
 }
 
-
-BT_HIDDEN
-int bin_info_set_build_id(struct bin_info *bin, uint8_t *build_id,
-		size_t build_id_len)
-{
-	if (!bin || !build_id) {
-		goto error;
-	}
-
-	bin->build_id = malloc(build_id_len);
-	if (!bin->build_id) {
-		goto error;
-	}
-
-	memcpy(bin->build_id, build_id, build_id_len);
-	bin->build_id_len = build_id_len;
-
-	/*
-	 * Reset the is_elf_only flag in case it had been set
-	 * previously, because we might find separate debug info using
-	 * the new build id information.
-	 */
-	bin->is_elf_only = false;
-
-	return 0;
-
-error:
-
-	return -1;
-}
-
 BT_HIDDEN
 int bin_info_set_debug_link(struct bin_info *bin, char *filename, uint32_t crc)
 {
@@ -687,6 +660,213 @@ int bin_info_get_nearest_symbol_from_section(Elf_Scn *scn, uint64_t addr,
 	g_free(_shdr);
 	return -1;
 }
+/**
+ * From a note section data buffer, check if it is a build id note.
+ *
+ * @param buf			Pointer to a note section
+ *
+ * @returns			1 on match, 0 if `buf` does not contain a
+ *				valid build id note
+ */
+static
+int is_build_id_note_section(uint8_t *buf)
+{
+	int ret = 0;
+	uint32_t name_sz, desc_sz, note_type;
+
+	/* The note section header has 3 32bit integer for the following:
+	 * - Section name size
+	 * - Description size
+	 * - Note type
+	 */
+	name_sz = (uint32_t) *buf;
+	buf += sizeof(name_sz);
+
+	buf += sizeof(desc_sz);
+
+	note_type = (uint32_t) *buf;
+	buf += sizeof(note_type);
+
+	/* Check the note type. */
+	if (note_type != NT_GNU_BUILD_ID) {
+		goto invalid;
+	}
+
+	/* Check the note name. */
+	if (memcmp(buf, BUILD_ID_NOTE_NAME, name_sz) != 0) {
+		goto invalid;
+	}
+
+	ret = 1;
+
+invalid:
+	return ret;
+}
+
+/**
+ *  From a build id note section data buffer, check if the build id it contains
+ *  is identical to the build id passed as parameter.
+ *
+ * @param file_build_id_note	Pointer to the file build id note section.
+ * @param build_id		Pointer to a build id to compare to.
+ * @param build_id_len		length of the build id.
+ *
+ * @returns			1 on match, 0 otherwise.
+ */
+static
+int compare_build_id_note_section(uint8_t *file_build_id_note, uint8_t *build_id, size_t build_id_len)
+{
+	uint32_t name_sz, desc_sz, note_type;
+
+	/* The note section header has 3 32bit integer for the following:
+	 * - Section name size
+	 * - Description size
+	 * - Note type
+	 */
+	name_sz = (uint32_t) *file_build_id_note;
+	file_build_id_note += sizeof(name_sz);
+	file_build_id_note += sizeof(desc_sz);
+	file_build_id_note += sizeof(note_type);
+
+	/*
+	 * Move the pointer pass the name char array. This corresponds to the
+	 * beginning of the description section. The description is the build
+	 * id in the case of a build id note.
+	 */
+	file_build_id_note += name_sz;
+
+	/*
+	 * Compare the binary build id with the supplied build id.
+	 */
+	if (memcmp(build_id, file_build_id_note, build_id_len) == 0) {
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * Checks if the build id stored in `bin` (bin->build_id) is matching the build
+ * id of the ondisk file (bin->elf_file).
+ *
+ * @param bin			bin_info instance
+ * @param build_id		build id to compare ot the on disk file
+ * @param build_id_len		length of the build id
+ *
+ * @returns			1 on if the build id of stored in `bin` matches
+ *				the build id of the ondisk file.
+ *				0 on if they are different or an error occured.
+ */
+static
+int is_build_id_matching(struct bin_info *bin, uint8_t *build_id,
+		size_t build_id_len)
+{
+	int ret, is_note_section, is_matching = 0;
+	Elf_Scn *curr_section = NULL, *next_section = NULL;
+	Elf_Data *note_data = NULL;
+	GElf_Shdr *curr_section_hdr = NULL;
+
+	if (!build_id) {
+		goto error;
+	}
+
+	/* Set ELF file if it hasn't been accessed yet. */
+	if (!bin->elf_file) {
+		ret = bin_info_set_elf_file(bin);
+		if (ret) {
+			/* Failed to set ELF file. */
+			goto error;
+		}
+	}
+
+	curr_section_hdr = g_new0(GElf_Shdr, 1);
+	if (!curr_section_hdr) {
+		goto error;
+	}
+
+	next_section = elf_nextscn(bin->elf_file, curr_section);
+	if (!next_section) {
+		goto error;
+	}
+
+	while (next_section) {
+		curr_section = next_section;
+		next_section = elf_nextscn(bin->elf_file, curr_section);
+
+		curr_section_hdr = gelf_getshdr(curr_section, curr_section_hdr);
+
+		if (!curr_section_hdr) {
+			goto error;
+		}
+
+		if (curr_section_hdr->sh_type != SHT_NOTE) {
+			continue;
+		}
+
+		note_data = elf_getdata(curr_section, NULL);
+		if (!note_data) {
+			goto error;
+		}
+
+		/* Check if the note is of the build-id type. */
+		is_note_section = is_build_id_note_section(note_data->d_buf);
+		if (!is_note_section)
+		{
+			continue;
+		}
+
+		/*
+		 * Compare the build id of the on-disk file and
+		 * the build id recorded in the trace.
+		 */
+		is_matching = compare_build_id_note_section(note_data->d_buf, build_id, build_id_len);
+		if (!is_matching) {
+			break;
+		}
+	}
+error:
+	g_free(curr_section_hdr);
+	return is_matching;
+}
+
+BT_HIDDEN
+int bin_info_set_build_id(struct bin_info *bin, uint8_t *build_id,
+		size_t build_id_len)
+{
+	if (!bin || !build_id) {
+		goto error;
+	}
+
+	/*
+	 * Check if the file found on the file system has the same build id
+	 * that what was recorded in the trace.
+	 */
+	bin->file_build_id_matches = is_build_id_matching(bin, build_id, build_id_len);
+	if(!bin->file_build_id_matches) {
+		printf_verbose("Supplied Build ID does not match Build ID of the "
+				"binary or library found on the file system.");
+		goto error;
+	}
+
+	bin->build_id = malloc(build_id_len);
+	if (!bin->build_id) {
+		goto error;
+	}
+
+	memcpy(bin->build_id, build_id, build_id_len);
+	bin->build_id_len = (size_t) build_id_len;
+
+	/*
+	 * Reset the is_elf_only flag in case it had been set
+	 * previously, because we might find separate debug info using
+	 * the new build id information.
+	 */
+	bin->is_elf_only = false;
+
+	return 0;
+
+error:
+	return -1;
+}
 
 /**
  * Get the name of the function containing a given address within an
@@ -918,6 +1098,14 @@ int bin_info_lookup_function_name(struct bin_info *bin, uint64_t addr,
 		goto error;
 	}
 
+	/*
+	 * If the bin_info has a build id but it does not match the build id
+	 * that was found on the file system, return an error.
+	 */
+	if (bin->build_id && !bin->file_build_id_matches) {
+		goto error;
+	}
+
 	/* Set DWARF info if it hasn't been accessed yet. */
 	if (!bin->dwarf_info && !bin->is_elf_only) {
 		ret = bin_info_set_dwarf_info(bin);
@@ -965,6 +1153,14 @@ int bin_info_get_bin_loc(struct bin_info *bin, uint64_t addr, char **bin_loc)
 		goto error;
 	}
 
+	/*
+	 * If the bin_info has a build id but it does not match the build id
+	 * that was found on the file system, return an error.
+	 */
+	if (bin->build_id && !bin->file_build_id_matches) {
+		goto error;
+	}
+
 	if (bin->is_pic) {
 		addr -= bin->low_addr;
 		ret = asprintf(&_bin_loc, "+%#0" PRIx64, addr);
@@ -1291,6 +1487,14 @@ int bin_info_lookup_source_location(struct bin_info *bin, uint64_t addr,
 		goto error;
 	}
 
+	/*
+	 * If the bin_info has a build id but it does not match the build id
+	 * that was found on the file system, return an error.
+	 */
+	if (bin->build_id && !bin->file_build_id_matches) {
+		goto error;
+	}
+
 	/* Set DWARF info if it hasn't been accessed yet. */
 	if (!bin->dwarf_info && !bin->is_elf_only) {
 		if (bin_info_set_dwarf_info(bin)) {

lib/debug-info.c

@@ -99,6 +99,14 @@ struct debug_info_source *debug_info_source_create_from_bin(struct bin_info *bin
 	struct debug_info_source *debug_info_src = NULL;
 	struct source_location *src_loc = NULL;
 
+	/*
+	 * If the build id of the binary or library does not match the one
+	 * recorded on the trace, return NULL.
+	 */
+	if (bin->build_id && !bin->file_build_id_matches) {
+		goto end;
+	}
+
 	debug_info_src = g_new0(struct debug_info_source, 1);
 
 	if (!debug_info_src) {
@@ -271,6 +279,14 @@ struct debug_info_source *proc_debug_info_sources_get_entry(
 	{
 		struct bin_info *bin = value;
 
+		/*
+		 * If the build ids in the trace and on the file don't match,
+		 * skip it.
+		 */
+		if (!bin->file_build_id_matches) {
+			continue;
+		}
+
 		if (!bin_info_has_address(value, ip)) {
 			continue;
 		}
@@ -379,7 +395,7 @@ void handle_statedump_build_id_event(struct debug_info *debug_info,
 	struct bt_definition *build_id_def = NULL;
 	struct definition_sequence *build_id_seq;
 	struct bin_info *bin = NULL;
-	int i;
+	int i, ret;
 	int64_t vpid;
 	uint64_t baddr;
 	uint8_t *build_id = NULL;
@@ -455,7 +471,11 @@ void handle_statedump_build_id_event(struct debug_info *debug_info,
 		goto end;
 	}
 
-	bin_info_set_build_id(bin, build_id, build_id_len);
+	ret = bin_info_set_build_id(bin, build_id, build_id_len);
+	if (ret) {
+		printf_verbose("Failed to set build id:  ret=%d", ret);
+		goto end;
+	}
 
 end:
 	free(build_id);