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x86/tools/relocs: Fix big section header tables

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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: Artem Savkov <asavkov@redhat.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Joe 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Artem Savkov 2018-11-29 16:56:15 +01:00 committed by Ingo Molnar
parent 93ddedaa5c
commit f36e7495dd
1 changed files with 45 additions and 29 deletions
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72
arch/x86/tools/relocs.c
View File

@ -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;
@ -366,27 +368,41 @@ 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)
@ -394,20 +410,20 @@ 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;