From db8e7fbb4c637ed5755b817d558af3310d9fa271 Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Fri, 11 Apr 2025 16:47:36 +0200 Subject: [PATCH] 5.1-7 - Add 0001-debugedit-Handle-unused-.debug_str_offsets-entries.patch Resolves: #RHEL-86684 debugedit: Handle unused .debug_str_offsets entries --- ...le-unused-.debug_str_offsets-entries.patch | 244 ++++++++++++++++++ debugedit.spec | 6 +- 2 files changed, 249 insertions(+), 1 deletion(-) create mode 100644 0001-debugedit-Handle-unused-.debug_str_offsets-entries.patch diff --git a/0001-debugedit-Handle-unused-.debug_str_offsets-entries.patch b/0001-debugedit-Handle-unused-.debug_str_offsets-entries.patch new file mode 100644 index 0000000..ef283ba --- /dev/null +++ b/0001-debugedit-Handle-unused-.debug_str_offsets-entries.patch @@ -0,0 +1,244 @@ +From 0add2fc587ff07e39bc3a22187c2425a129c7d41 Mon Sep 17 00:00:00 2001 +From: Mark Wielaard +Date: Mon, 7 Apr 2025 16:27:11 +0200 +Subject: [PATCH] debugedit: Handle unused .debug_str_offsets entries + +As a sanity check we would assert when rewriting a .debug_str index we +hadn't seen while processing the DWARF. This relies on the DWARF +producer/compiler to not emit strings that aren't used. So when +processing/rewriting the .debug_str_offsets we assume all indexes +point to .debugstr offsets we have seen before. + +This assumption doesn't seem to hold for clang++ at the moment. It +does put strings in the .debug_str section referenced from the +.debug_str_offsets section that aren't used anywhere else. So +debugedit will fail with an assert when processing such files. + +We don't want to process the .debug_str_offsets section multiple time +and possibly have to rewrite other str references in other +sections. So instead when we encounter an unseen/unused string we +replace it with a dummy string "". + +To help DWARF producers indentify these unused strings we keep a +reference to the original string table and produce a warning +explaining which .debug_str_offsets table at which index points to the +unseen .debug_str offset. + + debugedit: Warning, .debug_str_offsets table at offset ce2d0 index + [4213] .debug_str [48cad9] entry 'CrossThreadCopierBaseHelper' unused, + replacing with '' + + * tools/debugedit.c (debugedit_stridxentry): New static struct + stridxentry. + (struct strings): Add new field orig_data. + (create_dummy_debugedit_stridxentry): New function. + (string_find_new_entry): Add boolean argument accept_missing. + Return &debugedit_stridxentry if no existing string index + could be found. + (setup_strings): Fill in orig_data field. + (update_strings): New function to set orig_data field. + (orig_str): New function returns the original string at index. + (edit_strp): Call string_find_entry with false. + (update_str_offsets): Call string_find_entry with true, emit + warning if entry returned is &debugedit_stridxentry. + (edit_dwarf2): Call update_strings and + create_dummy_debugedit_stridxentry. + +https://sourceware.org/bugzilla/show_bug.cgi?id=32845 + +Signed-off-by: Mark Wielaard +--- + tools/debugedit.c | 89 +++++++++++++++++++++++++++++++++++++++++++---- + 1 file changed, 83 insertions(+), 6 deletions(-) + +diff --git a/tools/debugedit.c b/tools/debugedit.c +index 43f9cee65cf8..fcf8f7d6564b 100644 +--- a/tools/debugedit.c ++++ b/tools/debugedit.c +@@ -144,6 +144,15 @@ struct stridxentry + Strent *entry; /* Entry in the new table. */ + }; + ++/* Turns out we do need at least one replacement string when there are ++ strings that are never used in any of the debug sections, but that ++ turn up in the .debug_str_offsets. In that case (which really ++ shouldn't occur because it means the DWARF producer added unused ++ strings to the string table) we (warn and) replace the entry with ++ "". Call create_dummy_debugedit_stridxentry to add the ++ actual string. */ ++static struct stridxentry debugedit_stridxentry = { 0, NULL }; ++ + /* Storage for new string table entries. Keep together in memory to + quickly search through them with tsearch. */ + #define STRIDXENTRIES ((16 * 1024) / sizeof (struct stridxentry)) +@@ -157,6 +166,7 @@ struct strentblock + struct strings + { + Strtab *str_tab; /* The new string table. */ ++ Elf_Data orig_data; /* Original Elf_Data. */ + char *str_buf; /* New Elf_Data d_buf. */ + struct strmemblock *blocks; /* The first strmemblock. */ + struct strmemblock *last_block; /* The currently used strmemblock. */ +@@ -1119,6 +1129,32 @@ new_string_storage (struct strings *strings, size_t size) + return &strings->last_block->memory[stridx]; + } + ++static void ++create_dummy_debugedit_stridxentry (DSO *dso) ++{ ++ if (debugedit_stridxentry.entry != NULL) ++ { ++ fprintf (stderr, "debugedit: " ++ "create_dummy_debugedit_stridxentry called more than once."); ++ exit (-1); ++ } ++ ++ const char *dummy_name = ""; /* Kilroy was here */ ++ const size_t dummy_size = strlen (dummy_name) + 1; ++ ++ Strent *strent; ++ char* dummy_str = new_string_storage (&dso->debug_str, dummy_size); ++ if (dummy_str == NULL) ++ error (1, ENOMEM, "Couldn't allocate new string storage"); ++ memcpy (dummy_str, dummy_name, dummy_size); ++ strent = strtab_add_len (dso->debug_str.str_tab, dummy_str, dummy_size); ++ if (strent == NULL) ++ error (1, ENOMEM, "Could not create new string table entry"); ++ ++ debugedit_stridxentry.idx = (uint32_t) -1; ++ debugedit_stridxentry.entry = strent; ++} ++ + /* Comparison function used for tsearch. */ + static int + strent_compare (const void *a, const void *b) +@@ -1189,12 +1225,14 @@ string_find_new_entry (struct strings *strings, size_t old_idx) + } + + static struct stridxentry * +-string_find_entry (struct strings *strings, size_t old_idx) ++string_find_entry (struct strings *strings, size_t old_idx, bool accept_missing) + { + struct stridxentry **ret; + struct stridxentry key; + key.idx = old_idx; + ret = tfind (&key, &strings->strent_root, strent_compare); ++ if (accept_missing && ret == NULL) ++ return &debugedit_stridxentry; + assert (ret != NULL); /* Can only happen for a bad/non-existing old_idx. */ + return *ret; + } +@@ -1291,6 +1329,8 @@ static void + setup_strings (struct strings *strings) + { + strings->str_tab = strtab_init (false); ++ /* call update_strings to fill this in. */ ++ memset (&strings->orig_data, 0, sizeof (strings->orig_data)); + strings->str_buf = NULL; + strings->blocks = NULL; + strings->last_block = NULL; +@@ -1299,6 +1339,21 @@ setup_strings (struct strings *strings) + strings->strent_root = NULL; + } + ++static void ++update_strings (struct strings *strings, struct debug_section *sec) ++{ ++ if (sec->elf_data != NULL) ++ strings->orig_data = *sec->elf_data; ++} ++ ++static const char * ++orig_str (struct strings *strings, size_t idx) ++{ ++ if (idx < strings->orig_data.d_size) ++ return (const char *) strings->orig_data.d_buf + idx; ++ return ""; ++} ++ + /* Noop for tdestroy. */ + static void free_node (void *p __attribute__((__unused__))) { } + +@@ -1707,7 +1762,7 @@ edit_strp (DSO *dso, uint32_t form, unsigned char *ptr, int phase, + struct strings *strings = (form == DW_FORM_line_strp + ? &dso->debug_line_str : &dso->debug_str); + idx = do_read_32_relocated (ptr, sec); +- entry = string_find_entry (strings, idx); ++ entry = string_find_entry (strings, idx, false); + new_idx = strent_offset (entry->entry); + do_write_32_relocated (ptr, new_idx); + } +@@ -2791,6 +2846,7 @@ update_str_offsets (DSO *dso) + while (ptr < endp) + { + /* Read header, unit_length, version and padding. */ ++ unsigned char *index_start = ptr; + if (endp - ptr < 3 * 4) + break; + uint32_t unit_length = read_32 (ptr); +@@ -2803,13 +2859,21 @@ update_str_offsets (DSO *dso) + uint32_t padding = read_16 (ptr); + if (padding != 0) + break; ++ unsigned char *offstart = ptr; + + while (ptr < endidxp) + { + struct stridxentry *entry; + size_t idx, new_idx; + idx = do_read_32_relocated (ptr, str_off_sec); +- entry = string_find_entry (&dso->debug_str, idx); ++ entry = string_find_entry (&dso->debug_str, idx, true); ++ if (entry == &debugedit_stridxentry) ++ error (0, 0, "Warning, .debug_str_offsets table at offset %zx " ++ "index [%zd] .debug_str [%zx] entry '%s' unused, " ++ "replacing with ''\n", ++ (index_start - str_off_sec->data), ++ (ptr - offstart) / sizeof (uint32_t), idx, ++ orig_str (&dso->debug_str, idx)); + new_idx = strent_offset (entry->entry); + write_32_relocated (ptr, new_idx); + } +@@ -2963,6 +3027,9 @@ edit_dwarf2 (DSO *dso) + } + } + ++ update_strings (&dso->debug_str, &debug_sections[DEBUG_STR]); ++ update_strings (&dso->debug_line_str, &debug_sections[DEBUG_LINE_STR]); ++ + if (dso->ehdr.e_ident[EI_DATA] == ELFDATA2LSB) + { + do_read_16 = buf_read_ule16; +@@ -3211,7 +3278,8 @@ edit_dwarf2 (DSO *dso) + struct stridxentry *entry; + size_t idx, new_idx; + idx = do_read_32_relocated (ptr, macro_sec); +- entry = string_find_entry (&dso->debug_str, idx); ++ entry = string_find_entry (&dso->debug_str, idx, ++ false); + new_idx = strent_offset (entry->entry); + write_32_relocated (ptr, new_idx); + } +@@ -3265,8 +3333,17 @@ edit_dwarf2 (DSO *dso) + Make sure everything is in place for phase 1 updating of debug_info + references. */ + if (phase == 0 && need_strp_update) +- edit_dwarf2_any_str (dso, &dso->debug_str, +- &debug_sections[DEBUG_STR]); ++ { ++ /* We might need a dummy .debug_str entry for ++ .debug_str_offsets entries of unused strings. We have to ++ add it unconditionally when there is a .debug_str_offsets ++ section because we don't know if there are any such ++ entries. */ ++ if (debug_sections[DEBUG_STR_OFFSETS].data != NULL) ++ create_dummy_debugedit_stridxentry (dso); ++ edit_dwarf2_any_str (dso, &dso->debug_str, ++ &debug_sections[DEBUG_STR]); ++ } + if (phase == 0 && need_line_strp_update) + edit_dwarf2_any_str (dso, &dso->debug_line_str, + &debug_sections[DEBUG_LINE_STR]); +-- +2.49.0 + diff --git a/debugedit.spec b/debugedit.spec index 360da45..caa970a 100644 --- a/debugedit.spec +++ b/debugedit.spec @@ -1,6 +1,6 @@ Name: debugedit Version: 5.1 -Release: 6%{?dist} +Release: 7%{?dist} Summary: Tools and scripts for creating debuginfo and source file distributions, collect build-ids and rewrite source paths in DWARF data for debugging, tracing and profiling. License: GPL-3.0-or-later AND GPL-2.0-or-later AND LGPL-2.0-or-later URL: https://sourceware.org/debugedit/ @@ -50,6 +50,7 @@ Patch1: 0001-find-debuginfo-Check-files-are-writable-before-modif.patch Patch2: 0001-find-debuginfo-Fix-skip_mini-.gnu_debugdata-handling.patch patch3: 0001-find-debuginfo-Make-return-from-do_file-explicit.patch patch4: debugedit-5.1-binutils-tools-override.patch +patch5: 0001-debugedit-Handle-unused-.debug_str_offsets-entries.patch %description The debugedit project provides programs and scripts for creating @@ -91,6 +92,9 @@ make check %{?_smp_mflags} %{_mandir}/man1/find-debuginfo.1* %changelog +* Fri Apr 11 2025 Mark Wielaard - 5.1-7 +- Add 0001-debugedit-Handle-unused-.debug_str_offsets-entries.patch + * Fri Mar 21 2025 Martin Cermak - 5.1-6 - NVR bump and rebuild for RHEL-10.1