Commit f36e7495 authored by Artem Savkov's avatar Artem Savkov Committed by Ingo Molnar
Browse files

x86/tools/relocs: Fix big section header tables 



In case when the number of entries in the section header table is larger
then or equal to SHN_LORESERVE the size of the table is held in the sh_size
member of the initial entry in section header table instead of e_shnum.
Same with the string table index which is located in sh_link instead of
e_shstrndx.

This case is easily reproducible with KCFLAGS="-ffunction-sections",
bzImage build fails with "String table index out of bounds" error.

Signed-off-by: default avatarArtem Savkov <asavkov@redhat.com>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Cc: Eric W . Biederman <ebiederm@xmission.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181129155615.2594-1-asavkov@redhat.com


[ Simplify the die() lines. ]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 93ddedaa

arch/x86/tools/relocs.c

+45 −29
Original line number Diff line number Diff line
@@ -12,6 +12,8 @@ 
#define Elf_Sym			ElfW(Sym)



static Elf_Ehdr		ehdr;

static unsigned long	shnum;

static unsigned int	shstrndx;



struct relocs {

	uint32_t	*offset;
@@ -241,9 +243,9 @@ static const char *sec_name(unsigned shndx) 
{

	const char *sec_strtab;

	const char *name;

	sec_strtab = secs[ehdr.e_shstrndx].strtab;

	sec_strtab = secs[shstrndx].strtab;

	name = "<noname>";

	if (shndx < ehdr.e_shnum) {

	if (shndx < shnum) {

		name = sec_strtab + secs[shndx].shdr.sh_name;

	}

	else if (shndx == SHN_ABS) {
@@ -271,7 +273,7 @@ static const char *sym_name(const char *sym_strtab, Elf_Sym *sym) 
static Elf_Sym *sym_lookup(const char *symname)

{

	int i;

	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		struct section *sec = &secs[i];

		long nsyms;

		char *strtab;
@@ -366,48 +368,62 @@ static void read_ehdr(FILE *fp) 
	ehdr.e_shnum     = elf_half_to_cpu(ehdr.e_shnum);

	ehdr.e_shstrndx  = elf_half_to_cpu(ehdr.e_shstrndx);



	if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {

	shnum = ehdr.e_shnum;

	shstrndx = ehdr.e_shstrndx;



	if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN))

		die("Unsupported ELF header type\n");

	}

	if (ehdr.e_machine != ELF_MACHINE) {

	if (ehdr.e_machine != ELF_MACHINE)

		die("Not for %s\n", ELF_MACHINE_NAME);

	}

	if (ehdr.e_version != EV_CURRENT) {

	if (ehdr.e_version != EV_CURRENT)

		die("Unknown ELF version\n");

	}

	if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) {

	if (ehdr.e_ehsize != sizeof(Elf_Ehdr))

		die("Bad Elf header size\n");

	}

	if (ehdr.e_phentsize != sizeof(Elf_Phdr)) {

	if (ehdr.e_phentsize != sizeof(Elf_Phdr))

		die("Bad program header entry\n");

	}

	if (ehdr.e_shentsize != sizeof(Elf_Shdr)) {

	if (ehdr.e_shentsize != sizeof(Elf_Shdr))

		die("Bad section header entry\n");





	if (shnum == SHN_UNDEF || shstrndx == SHN_XINDEX) {

		Elf_Shdr shdr;



		if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0)

			die("Seek to %d failed: %s\n", ehdr.e_shoff, strerror(errno));



		if (fread(&shdr, sizeof(shdr), 1, fp) != 1)

			die("Cannot read initial ELF section header: %s\n", strerror(errno));



		if (shnum == SHN_UNDEF)

			shnum = elf_xword_to_cpu(shdr.sh_size);



		if (shstrndx == SHN_XINDEX)

			shstrndx = elf_word_to_cpu(shdr.sh_link);

	}

	if (ehdr.e_shstrndx >= ehdr.e_shnum) {



	if (shstrndx >= shnum)

		die("String table index out of bounds\n");

}

}



static void read_shdrs(FILE *fp)

{

	int i;

	Elf_Shdr shdr;



	secs = calloc(ehdr.e_shnum, sizeof(struct section));

	secs = calloc(shnum, sizeof(struct section));

	if (!secs) {

		die("Unable to allocate %d section headers\n",

		    ehdr.e_shnum);

		    shnum);

	}

	if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {

		die("Seek to %d failed: %s\n",

			ehdr.e_shoff, strerror(errno));

	}

	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		struct section *sec = &secs[i];

		if (fread(&shdr, sizeof(shdr), 1, fp) != 1)

			die("Cannot read ELF section headers %d/%d: %s\n",

			    i, ehdr.e_shnum, strerror(errno));

			    i, shnum, strerror(errno));

		sec->shdr.sh_name      = elf_word_to_cpu(shdr.sh_name);

		sec->shdr.sh_type      = elf_word_to_cpu(shdr.sh_type);

		sec->shdr.sh_flags     = elf_xword_to_cpu(shdr.sh_flags);
@@ -418,7 +434,7 @@ static void read_shdrs(FILE *fp) 
		sec->shdr.sh_info      = elf_word_to_cpu(shdr.sh_info);

		sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);

		sec->shdr.sh_entsize   = elf_xword_to_cpu(shdr.sh_entsize);

		if (sec->shdr.sh_link < ehdr.e_shnum)

		if (sec->shdr.sh_link < shnum)

			sec->link = &secs[sec->shdr.sh_link];

	}
@@ -427,7 +443,7 @@ static void read_shdrs(FILE *fp) 
static void read_strtabs(FILE *fp)

{

	int i;

	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		struct section *sec = &secs[i];

		if (sec->shdr.sh_type != SHT_STRTAB) {

			continue;
@@ -452,7 +468,7 @@ static void read_strtabs(FILE *fp) 
static void read_symtabs(FILE *fp)

{

	int i,j;

	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		struct section *sec = &secs[i];

		if (sec->shdr.sh_type != SHT_SYMTAB) {

			continue;
@@ -485,7 +501,7 @@ static void read_symtabs(FILE *fp) 
static void read_relocs(FILE *fp)

{

	int i,j;

	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		struct section *sec = &secs[i];

		if (sec->shdr.sh_type != SHT_REL_TYPE) {

			continue;
@@ -528,7 +544,7 @@ static void print_absolute_symbols(void) 


	printf("Absolute symbols\n");

	printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");

	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		struct section *sec = &secs[i];

		char *sym_strtab;

		int j;
@@ -566,7 +582,7 @@ static void print_absolute_relocs(void) 
	else

		format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32"  %s\n";



	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		struct section *sec = &secs[i];

		struct section *sec_applies, *sec_symtab;

		char *sym_strtab;
@@ -650,7 +666,7 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel, 
{

	int i;

	/* Walk through the relocations */

	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		char *sym_strtab;

		Elf_Sym *sh_symtab;

		struct section *sec_applies, *sec_symtab;
@@ -706,7 +722,7 @@ static Elf_Addr per_cpu_load_addr; 
static void percpu_init(void)

{

	int i;

	for (i = 0; i < ehdr.e_shnum; i++) {

	for (i = 0; i < shnum; i++) {

		ElfW(Sym) *sym;

		if (strcmp(sec_name(i), ".data..percpu"))

			continue;

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