Use the symtab's sh_link to get the string table section.

This is technically more correct than looking for ".strtab" and allows
us to get rid of unportable ELF_STRTAB.

We can also get rid of the hack for some incorrect ELF files since we
no longer try to apply relocations for the string table.

From Mark Johnston, markj@FreeBSD

2 files changed, 27 insertions, 15 deletions

diff --git a/usr.bin/ctfconv/ctfconv.c b/usr.bin/ctfconv/ctfconv.c
index 31eb7bc7fb0..a7f65090a8c 100644
--- a/usr.bin/ctfconv/ctfconv.c
+++ b/usr.bin/ctfconv/ctfconv.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ctfconv.c,v 1.15 2017/11/03 12:55:43 mpi Exp $ */
+/*	$OpenBSD: ctfconv.c,v 1.16 2017/11/06 14:59:27 mpi Exp $ */
 
 /*
  * Copyright (c) 2016-2017 Martin Pieuchot
@@ -60,7 +60,7 @@ void		 dump_obj(struct itype *, int *);
 int		 iself(const char *, size_t);
 int		 elf_getshstab(const char *, size_t, const char **, size_t *);
 ssize_t		 elf_getsymtab(const char *, size_t, const char *, size_t,
-		     const Elf_Sym **, size_t *);
+		     const Elf_Sym **, size_t *, const char **, size_t *);
 ssize_t		 elf_getsection(char *, size_t, const char *, const char *,
 		     size_t, const char **, size_t *);
 
@@ -221,15 +221,11 @@ elf_convert(char *p, size_t filesize)
 	if (elf_getshstab(p, filesize, &shstab, &shstabsz))
 		return 1;
 
-	/* Find symbol table location and number of symbols. */
-	if (elf_getsymtab(p, filesize, shstab, shstabsz, &symtab, &nsymb) == -1)
+	/* Find symbol table and associated string table. */
+	if (elf_getsymtab(p, filesize, shstab, shstabsz, &symtab, &nsymb,
+	    &strtab, &strtabsz) == -1)
 		warnx("symbol table not found");
 
-	/* Find string table location and size. */
-	if (elf_getsection(p, filesize, ELF_STRTAB, shstab, shstabsz, &strtab,
-	    &strtabsz) == -1)
-		warnx("string table not found");
-
 	/* Find abbreviation location and size. */
 	if (elf_getsection(p, filesize, DEBUG_ABBREV, shstab, shstabsz, &abbuf,
 	    &ablen) == -1) {
diff --git a/usr.bin/ctfconv/elf.c b/usr.bin/ctfconv/elf.c
index b7b2c542517..0bd026ebe86 100644
--- a/usr.bin/ctfconv/elf.c
+++ b/usr.bin/ctfconv/elf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: elf.c,v 1.7 2017/10/27 08:33:46 mpi Exp $ */
+/*	$OpenBSD: elf.c,v 1.8 2017/11/06 14:59:27 mpi Exp $ */
 
 /*
  * Copyright (c) 2016 Martin Pieuchot <mpi@openbsd.org>
@@ -104,14 +104,16 @@ elf_getshstab(const char *p, size_t filesize, const char **shstab,
 
 ssize_t
 elf_getsymtab(const char *p, size_t filesize, const char *shstab,
-    size_t shstabsz, const Elf_Sym **symtab, size_t *nsymb)
+    size_t shstabsz, const Elf_Sym **symtab, size_t *nsymb, const char **strtab,
+    size_t *strtabsz)
 {
 	Elf_Ehdr	*eh = (Elf_Ehdr *)p;
-	Elf_Shdr	*sh;
+	Elf_Shdr	*sh, *symsh;
 	size_t		 snlen;
 	ssize_t		 i;
 
 	snlen = strlen(ELF_SYMTAB);
+	symsh = NULL;
 
 	for (i = 0; i < eh->e_shnum; i++) {
 		sh = (Elf_Shdr *)(p + eh->e_shoff + i * eh->e_shentsize);
@@ -133,12 +135,26 @@ elf_getsymtab(const char *p, size_t filesize, const char *shstab,
 				*symtab = (Elf_Sym *)(p + sh->sh_offset);
 			if (nsymb != NULL)
 				*nsymb = (sh->sh_size / sh->sh_entsize);
+			symsh = sh;
 
-			return i;
+			break;
 		}
 	}
 
-	return -1;
+	if (symsh == NULL || (symsh->sh_link >= eh->e_shnum))
+		return -1;
+
+	sh = (Elf_Shdr *)(p + eh->e_shoff + symsh->sh_link * eh->e_shentsize);
+
+	if ((sh->sh_offset + sh->sh_size) > filesize)
+		return -1;
+
+	if (strtab != NULL)
+		*strtab = p + sh->sh_offset;
+	if (strtabsz != NULL)
+		*strtabsz = sh->sh_size;
+
+	return i;
 }
 
 ssize_t
@@ -240,7 +256,7 @@ elf_reloc_apply(const char *p, size_t filesize, const char *shstab,
 
 	/* Find symbol table location and number of symbols. */
 	symtabidx = elf_getsymtab(p, filesize, shstab, shstabsz, &symtab,
-	    &nsymb);
+	    &nsymb, NULL, NULL);
 	if (symtabidx == -1) {
 		warnx("symbol table not found");
 		return;