vapier 15/02/22 02:27:39 Modified: scanelf.c Log: scanelf: rework interp lookup Prefer PT_INTERP over the section headers since that gets used at runtime. Add verification to the pointer we do find.
Revision Changes Path 1.274 pax-utils/scanelf.c file : http://sources.gentoo.org/viewvc.cgi/gentoo-projects/pax-utils/scanelf.c?rev=1.274&view=markup plain: http://sources.gentoo.org/viewvc.cgi/gentoo-projects/pax-utils/scanelf.c?rev=1.274&content-type=text/plain diff : http://sources.gentoo.org/viewvc.cgi/gentoo-projects/pax-utils/scanelf.c?r1=1.273&r2=1.274 Index: scanelf.c =================================================================== RCS file: /var/cvsroot/gentoo-projects/pax-utils/scanelf.c,v retrieving revision 1.273 retrieving revision 1.274 diff -u -r1.273 -r1.274 --- scanelf.c 22 Feb 2015 01:38:28 -0000 1.273 +++ scanelf.c 22 Feb 2015 02:27:39 -0000 1.274 @@ -1,13 +1,13 @@ /* * Copyright 2003-2012 Gentoo Foundation * Distributed under the terms of the GNU General Public License v2 - * $Header: /var/cvsroot/gentoo-projects/pax-utils/scanelf.c,v 1.273 2015/02/22 01:38:28 vapier Exp $ + * $Header: /var/cvsroot/gentoo-projects/pax-utils/scanelf.c,v 1.274 2015/02/22 02:27:39 vapier Exp $ * * Copyright 2003-2012 Ned Ludd - <[email protected]> * Copyright 2004-2012 Mike Frysinger - <[email protected]> */ -static const char rcsid[] = "$Id: scanelf.c,v 1.273 2015/02/22 01:38:28 vapier Exp $"; +static const char rcsid[] = "$Id: scanelf.c,v 1.274 2015/02/22 02:27:39 vapier Exp $"; const char argv0[] = "scanelf"; #include "paxinc.h" @@ -1069,37 +1069,51 @@ } static char *scanelf_file_interp(elfobj *elf, char *found_interp) { - void *strtbl_void; + uint64_t offset = 0; if (!show_interp) return NULL; - strtbl_void = elf_findsecbyname(elf, ".interp"); - - if (strtbl_void) { -#define SHOW_INTERP(B) \ - if (elf->elf_class == ELFCLASS ## B) { \ - Elf ## B ## _Shdr *strtbl = SHDR ## B (strtbl_void); \ - *found_interp = 1; \ - return (be_wewy_wewy_quiet ? NULL : elf->data + EGET(strtbl->sh_offset)); \ - } - SHOW_INTERP(32) - SHOW_INTERP(64) - } else if (elf->phdr) { + if (elf->phdr) { /* Walk all the program headers to find the PT_INTERP */ #define SHOW_PT_INTERP(B) \ if (elf->elf_class == ELFCLASS ## B) { \ - unsigned long i; \ - Elf ## B ## _Ehdr *ehdr = EHDR ## B (elf->ehdr); \ - Elf ## B ## _Phdr *phdr = PHDR ## B (elf->phdr); \ - for (i = 0; i < EGET(ehdr->e_phnum); i++) { \ - if (EGET(phdr[i].p_type) != PT_INTERP) \ - continue; \ - *found_interp = 1; \ - return (be_wewy_wewy_quiet ? NULL : elf->data + EGET(phdr[i].p_offset)); \ - } \ + size_t i; \ + Elf ## B ## _Ehdr *ehdr = EHDR ## B (elf->ehdr); \ + Elf ## B ## _Phdr *phdr = PHDR ## B (elf->phdr); \ + for (i = 0; i < EGET(ehdr->e_phnum); ++i) { \ + if (EGET(phdr[i].p_type) == PT_INTERP) { \ + offset = EGET(phdr[i].p_offset); \ + break; \ + } \ + } \ } SHOW_PT_INTERP(32) SHOW_PT_INTERP(64) + } else if (elf->shdr) { + /* Use the section headers to find it */ + void *strtbl_void = elf_findsecbyname(elf, ".interp"); + +#define SHOW_INTERP(B) \ + if (elf->elf_class == ELFCLASS ## B) { \ + Elf ## B ## _Shdr *strtbl = SHDR ## B (strtbl_void); \ + offset = EGET(strtbl->sh_offset); \ + } + if (strtbl_void) { + SHOW_INTERP(32) + SHOW_INTERP(64) + } + } + + /* Validate the pointer even if we don't use it in output */ + if (offset && offset <= (uint64_t)elf->len) { + char *interp = elf->data + offset; + + /* If it isn't a C pointer, it's garbage */ + if (memchr(interp, 0, elf->len - offset)) { + *found_interp = 1; + if (!be_wewy_wewy_quiet) + return interp; + } } return NULL;
