Commit message: support ld build id printing.
CVE: CVE-2014-9620
CWE: CWE-399
Vulnerability description: The ELF parser in file 5.08 through 5.21 allows remote attackers to cause a denial of service via a large number of notes.

Project: file
File: readelf.c

donote(struct magic_set *ms, void *vbuf, size_t offset, size_t size,
    int clazz, int swap, size_t align, int *flags)
{
	Elf32_Nhdr nh32;
	Elf64_Nhdr nh64;
	size_t noff, doff;
#ifdef ELFCORE
	int os_style = -1;
#endif
	uint32_t namesz, descsz;
	unsigned char *nbuf = CAST(unsigned char *, vbuf);

	(void)memcpy(xnh_addr, &nbuf[offset], xnh_sizeof);
	offset += xnh_sizeof;

	namesz = xnh_namesz;
	descsz = xnh_descsz;
	if ((namesz == 0) && (descsz == 0)) {
		/*
		 * We're out of note headers.
		 */
		return (offset >= size) ? offset : size;
	}

	if (namesz & 0x80000000) {
	    (void)file_printf(ms, ", bad note name size 0x%lx",
		(unsigned long)namesz);
	    return offset;
	}

	if (descsz & 0x80000000) {
	    (void)file_printf(ms, ", bad note description size 0x%lx",
		(unsigned long)descsz);
	    return offset;
	}


	noff = offset;
	doff = ELF_ALIGN(offset + namesz);

	if (offset + namesz > size) {
		/*
		 * We're past the end of the buffer.
		 */
		return doff;
	}

	offset = ELF_ALIGN(doff + descsz);
	if (doff + descsz > size) {
		/*
		 * We're past the end of the buffer.
		 */
		return (offset >= size) ? offset : size;
	}

	if (*flags & FLAGS_DID_NOTE)
		goto core;

	if (namesz == 4 && strcmp((char *)&nbuf[noff], "GNU") == 0 &&
	    xnh_type == NT_GNU_VERSION && descsz == 16) {
		uint32_t desc[4];
		(void)memcpy(desc, &nbuf[doff], sizeof(desc));

		if (file_printf(ms, ", for GNU/") == -1)
			return size;
		switch (elf_getu32(swap, desc[0])) {
		case GNU_OS_LINUX:
			if (file_printf(ms, "Linux") == -1)
				return size;
			break;
		case GNU_OS_HURD:
			if (file_printf(ms, "Hurd") == -1)
				return size;
			break;
		case GNU_OS_SOLARIS:
			if (file_printf(ms, "Solaris") == -1)
				return size;
			break;
		case GNU_OS_KFREEBSD:
			if (file_printf(ms, "kFreeBSD") == -1)
				return size;
			break;
		case GNU_OS_KNETBSD:
			if (file_printf(ms, "kNetBSD") == -1)
				return size;
			break;
		default:
			if (file_printf(ms, "<unknown>") == -1)
				return size; 
		}
		if (file_printf(ms, " %d.%d.%d", elf_getu32(swap, desc[1]),
		    elf_getu32(swap, desc[2]), elf_getu32(swap, desc[3])) == -1)
			return size;
		*flags |= FLAGS_DID_NOTE;
		return size;
	}

	if (namesz == 7 && strcmp((char *)&nbuf[noff], "NetBSD") == 0 &&
	    xnh_type == NT_NETBSD_VERSION && descsz == 4) {
		uint32_t desc;
		(void)memcpy(&desc, &nbuf[doff], sizeof(desc));
		desc = elf_getu32(swap, desc);

		if (file_printf(ms, ", for NetBSD") == -1)
			return size;
		/*
		 * The version number used to be stuck as 199905, and was thus
		 * basically content-free.  Newer versions of NetBSD have fixed
		 * this and now use the encoding of __NetBSD_Version__:
		 *
		 *	MMmmrrpp00
		 *
		 * M = major version
		 * m = minor version
		 * r = release ["",A-Z,Z[A-Z] but numeric]
		 * p = patchlevel
		 */
		if (desc > 100000000U) {
			uint32_t ver_patch = (desc / 100) % 100;
			uint32_t ver_rel = (desc / 10000) % 100;
			uint32_t ver_min = (desc / 1000000) % 100;
			uint32_t ver_maj = desc / 100000000;

			if (file_printf(ms, " %u.%u", ver_maj, ver_min) == -1)
				return size;
			if (ver_rel == 0 && ver_patch != 0) {
				if (file_printf(ms, ".%u", ver_patch) == -1)
					return size;
			} else if (ver_rel != 0) {
				while (ver_rel > 26) {
					if (file_printf(ms, "Z") == -1)
						return size;
					ver_rel -= 26;
				}
				if (file_printf(ms, "%c", 'A' + ver_rel - 1)
				    == -1)
					return size;
			}
		}
		*flags |= FLAGS_DID_NOTE;
		return size;
	}

	if (namesz == 8 && strcmp((char *)&nbuf[noff], "FreeBSD") == 0 &&
	    xnh_type == NT_FREEBSD_VERSION && descsz == 4) {
		uint32_t desc;
		(void)memcpy(&desc, &nbuf[doff], sizeof(desc));
		desc = elf_getu32(swap, desc);
		if (file_printf(ms, ", for FreeBSD") == -1)
			return size;

		/*
		 * Contents is __FreeBSD_version, whose relation to OS
		 * versions is defined by a huge table in the Porter's
		 * Handbook.  This is the general scheme:
		 * 
		 * Releases:
		 * 	Mmp000 (before 4.10)
		 * 	Mmi0p0 (before 5.0)
		 * 	Mmm0p0
		 * 
		 * Development branches:
		 * 	Mmpxxx (before 4.6)
		 * 	Mmp1xx (before 4.10)
		 * 	Mmi1xx (before 5.0)
		 * 	M000xx (pre-M.0)
		 * 	Mmm1xx
		 * 
		 * M = major version
		 * m = minor version
		 * i = minor version increment (491000 -> 4.10)
		 * p = patchlevel
		 * x = revision
		 * 
		 * The first release of FreeBSD to use ELF by default
		 * was version 3.0.
		 */
		if (desc == 460002) {
			if (file_printf(ms, " 4.6.2") == -1)
				return size;
		} else if (desc < 460100) {
			if (file_printf(ms, " %d.%d", desc / 100000,
			    desc / 10000 % 10) == -1)
				return size;
			if (desc / 1000 % 10 > 0)
				if (file_printf(ms, ".%d", desc / 1000 % 10)
				    == -1)
					return size;
			if ((desc % 1000 > 0) || (desc % 100000 == 0))
				if (file_printf(ms, " (%d)", desc) == -1)
					return size;
		} else if (desc < 500000) {
			if (file_printf(ms, " %d.%d", desc / 100000,
			    desc / 10000 % 10 + desc / 1000 % 10) == -1)
				return size;
			if (desc / 100 % 10 > 0) {
				if (file_printf(ms, " (%d)", desc) == -1)
					return size;
			} else if (desc / 10 % 10 > 0) {
				if (file_printf(ms, ".%d", desc / 10 % 10)
				    == -1)
					return size;
			}
		} else {
			if (file_printf(ms, " %d.%d", desc / 100000,
			    desc / 1000 % 100) == -1)
				return size;
			if ((desc / 100 % 10 > 0) ||
			    (desc % 100000 / 100 == 0)) {
				if (file_printf(ms, " (%d)", desc) == -1)
					return size;
			} else if (desc / 10 % 10 > 0) {
				if (file_printf(ms, ".%d", desc / 10 % 10)
				    == -1)
					return size;
			}
		}
		*flags |= FLAGS_DID_NOTE;
		return size;
	}

	if (namesz == 8 && strcmp((char *)&nbuf[noff], "OpenBSD") == 0 &&
	    xnh_type == NT_OPENBSD_VERSION && descsz == 4) {
		if (file_printf(ms, ", for OpenBSD") == -1)
			return size;
		/* Content of note is always 0 */
		*flags |= FLAGS_DID_NOTE;
		return size;
	}

	if (namesz == 10 && strcmp((char *)&nbuf[noff], "DragonFly") == 0 &&
	    xnh_type == NT_DRAGONFLY_VERSION && descsz == 4) {
		uint32_t desc;
		if (file_printf(ms, ", for DragonFly") == -1)
			return size;
		(void)memcpy(&desc, &nbuf[doff], sizeof(desc));
		desc = elf_getu32(swap, desc);
		if (file_printf(ms, " %d.%d.%d", desc / 100000,
		    desc / 10000 % 10, desc % 10000) == -1)
			return size;
		*flags |= FLAGS_DID_NOTE;
		return size;
	}

core:
	/*
	 * Sigh.  The 2.0.36 kernel in Debian 2.1, at
	 * least, doesn't correctly implement name
	 * sections, in core dumps, as specified by
	 * the "Program Linking" section of "UNIX(R) System
	 * V Release 4 Programmer's Guide: ANSI C and
	 * Programming Support Tools", because my copy
	 * clearly says "The first 'namesz' bytes in 'name'
	 * contain a *null-terminated* [emphasis mine]
	 * character representation of the entry's owner
	 * or originator", but the 2.0.36 kernel code
	 * doesn't include the terminating null in the
	 * name....
	 */
	if ((namesz == 4 && strncmp((char *)&nbuf[noff], "CORE", 4) == 0) ||
	    (namesz == 5 && strcmp((char *)&nbuf[noff], "CORE") == 0)) {
		os_style = OS_STYLE_SVR4;
	} 

	if ((namesz == 8 && strcmp((char *)&nbuf[noff], "FreeBSD") == 0)) {
		os_style = OS_STYLE_FREEBSD;
	}

	if ((namesz >= 11 && strncmp((char *)&nbuf[noff], "NetBSD-CORE", 11)
	    == 0)) {
		os_style = OS_STYLE_NETBSD;
	}

#ifdef ELFCORE
	if ((*flags & FLAGS_DID_CORE) != 0)
		return size;

	if (os_style != -1 && (*flags & FLAGS_DID_CORE_STYLE) == 0) {
		if (file_printf(ms, ", %s-style", os_style_names[os_style])
		    == -1)
			return size;
		*flags |= FLAGS_DID_CORE_STYLE;
	}

	switch (os_style) {
	case OS_STYLE_NETBSD:
		if (xnh_type == NT_NETBSD_CORE_PROCINFO) {
			uint32_t signo;
			/*
			 * Extract the program name.  It is at
			 * offset 0x7c, and is up to 32-bytes,
			 * including the terminating NUL.
			 */
			if (file_printf(ms, ", from '%.31s'",
			    &nbuf[doff + 0x7c]) == -1)
				return size;
			
			/*
			 * Extract the signal number.  It is at
			 * offset 0x08.
			 */
			(void)memcpy(&signo, &nbuf[doff + 0x08],
			    sizeof(signo));
			if (file_printf(ms, " (signal %u)",
			    elf_getu32(swap, signo)) == -1)
				return size;
			*flags |= FLAGS_DID_CORE;
			return size;
		}
		break;

	default:
		if (xnh_type == NT_PRPSINFO && *flags & FLAGS_IS_CORE) {
			size_t i, j;
			unsigned char c;
			/*
			 * Extract the program name.  We assume
			 * it to be 16 characters (that's what it
			 * is in SunOS 5.x and Linux).
			 *
			 * Unfortunately, it's at a different offset
			 * in various OSes, so try multiple offsets.
			 * If the characters aren't all printable,
			 * reject it.
			 */
			for (i = 0; i < NOFFSETS; i++) {
				unsigned char *cname, *cp;
				size_t reloffset = prpsoffsets(i);
				size_t noffset = doff + reloffset;
				size_t k;
				for (j = 0; j < 16; j++, noffset++,
				    reloffset++) {
					/*
					 * Make sure we're not past
					 * the end of the buffer; if
					 * we are, just give up.
					 */
					if (noffset >= size)
						goto tryanother;

					/*
					 * Make sure we're not past
					 * the end of the contents;
					 * if we are, this obviously
					 * isn't the right offset.
					 */
					if (reloffset >= descsz)
						goto tryanother;

					c = nbuf[noffset];
					if (c == '\0') {
						/*
						 * A '\0' at the
						 * beginning is
						 * obviously wrong.
						 * Any other '\0'
						 * means we're done.
						 */
						if (j == 0)
							goto tryanother;
						else
							break;
					} else {
						/*
						 * A nonprintable
						 * character is also
						 * wrong.
						 */
						if (!isprint(c) || isquote(c))
							goto tryanother;
					}
				}
				/*
				 * Well, that worked.
				 */

				/*
				 * Try next offsets, in case this match is
				 * in the middle of a string.
				 */
				for (k = i + 1 ; k < NOFFSETS ; k++) {
					size_t no;
					int adjust = 1;
					if (prpsoffsets(k) >= prpsoffsets(i))
						continue;
					for (no = doff + prpsoffsets(k);
					     no < doff + prpsoffsets(i); no++)
						adjust = adjust
						         && isprint(nbuf[no]);
					if (adjust)
						i = k;
				}

				cname = (unsigned char *)
				    &nbuf[doff + prpsoffsets(i)];
				for (cp = cname; *cp && isprint(*cp); cp++)
					continue;
				/*
				 * Linux apparently appends a space at the end
				 * of the command line: remove it.
				 */
				while (cp > cname && isspace(cp[-1]))
					cp--;
				if (file_printf(ms, ", from '%.*s'",
				    (int)(cp - cname), cname) == -1)
					return size;
				*flags |= FLAGS_DID_CORE;
				return size;

			tryanother:
				;
			}
		}
		break;
	}
#endif
	return offset;
}