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linux/arch/s390/kernel/module.c
Hendrik Brueckner 3164a3cbf8 [S390] kprobes: add parameter check to module_free() 
When unregistering kprobes, kprobes calls module_free() and
always passes NULL for the mod parameter.  Add a check to
prevent NULL pointer dereferences.

See commit 740a8de079 for more details.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-06-08 18:58:23 +02:00

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/*
* arch/s390/kernel/module.c - Kernel module help for s390.
*
* S390 version
* Copyright (C) 2002, 2003 IBM Deutschland Entwicklung GmbH,
* IBM Corporation
* Author(s): Arnd Bergmann (arndb@de.ibm.com)
* Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* based on i386 version
* Copyright (C) 2001 Rusty Russell.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/module.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/moduleloader.h>
#include <linux/bug.h>
#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt , ...)
#endif
#ifndef CONFIG_64BIT
#define PLT_ENTRY_SIZE 12
#else /* CONFIG_64BIT */
#define PLT_ENTRY_SIZE 20
#endif /* CONFIG_64BIT */
void *module_alloc(unsigned long size)
{
if (size == 0)
return NULL;
return vmalloc(size);
}
/* Free memory returned from module_alloc */
void module_free(struct module *mod, void *module_region)
{
if (mod) {
vfree(mod->arch.syminfo);
mod->arch.syminfo = NULL;
}
vfree(module_region);
}
static void
check_rela(Elf_Rela *rela, struct module *me)
{
struct mod_arch_syminfo *info;
info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
switch (ELF_R_TYPE (rela->r_info)) {
case R_390_GOT12: /* 12 bit GOT offset. */
case R_390_GOT16: /* 16 bit GOT offset. */
case R_390_GOT20: /* 20 bit GOT offset. */
case R_390_GOT32: /* 32 bit GOT offset. */
case R_390_GOT64: /* 64 bit GOT offset. */
case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
if (info->got_offset == -1UL) {
info->got_offset = me->arch.got_size;
me->arch.got_size += sizeof(void*);
}
break;
case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
case R_390_PLT32: /* 32 bit PC relative PLT address. */
case R_390_PLT64: /* 64 bit PC relative PLT address. */
case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
if (info->plt_offset == -1UL) {
info->plt_offset = me->arch.plt_size;
me->arch.plt_size += PLT_ENTRY_SIZE;
}
break;
case R_390_COPY:
case R_390_GLOB_DAT:
case R_390_JMP_SLOT:
case R_390_RELATIVE:
/* Only needed if we want to support loading of
modules linked with -shared. */
break;
}
}
/*
* Account for GOT and PLT relocations. We can't add sections for
* got and plt but we can increase the core module size.
*/
int
module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
char *secstrings, struct module *me)
{
Elf_Shdr *symtab;
Elf_Sym *symbols;
Elf_Rela *rela;
char *strings;
int nrela, i, j;
/* Find symbol table and string table. */
symtab = NULL;
for (i = 0; i < hdr->e_shnum; i++)
switch (sechdrs[i].sh_type) {
case SHT_SYMTAB:
symtab = sechdrs + i;
break;
}
if (!symtab) {
printk(KERN_ERR "module %s: no symbol table\n", me->name);
return -ENOEXEC;
}
/* Allocate one syminfo structure per symbol. */
me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
me->arch.syminfo = vmalloc(me->arch.nsyms *
sizeof(struct mod_arch_syminfo));
if (!me->arch.syminfo)
return -ENOMEM;
symbols = (void *) hdr + symtab->sh_offset;
strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
for (i = 0; i < me->arch.nsyms; i++) {
if (symbols[i].st_shndx == SHN_UNDEF &&
strcmp(strings + symbols[i].st_name,
"_GLOBAL_OFFSET_TABLE_") == 0)
/* "Define" it as absolute. */
symbols[i].st_shndx = SHN_ABS;
me->arch.syminfo[i].got_offset = -1UL;
me->arch.syminfo[i].plt_offset = -1UL;
me->arch.syminfo[i].got_initialized = 0;
me->arch.syminfo[i].plt_initialized = 0;
}
/* Search for got/plt relocations. */
me->arch.got_size = me->arch.plt_size = 0;
for (i = 0; i < hdr->e_shnum; i++) {
if (sechdrs[i].sh_type != SHT_RELA)
continue;
nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
rela = (void *) hdr + sechdrs[i].sh_offset;
for (j = 0; j < nrela; j++)
check_rela(rela + j, me);
}
/* Increase core size by size of got & plt and set start
offsets for got and plt. */
me->core_size = ALIGN(me->core_size, 4);
me->arch.got_offset = me->core_size;
me->core_size += me->arch.got_size;
me->arch.plt_offset = me->core_size;
me->core_size += me->arch.plt_size;
return 0;
}
int
apply_relocate(Elf_Shdr *sechdrs, const char *strtab, unsigned int symindex,
unsigned int relsec, struct module *me)
{
printk(KERN_ERR "module %s: RELOCATION unsupported\n",
me->name);
return -ENOEXEC;
}
static int
apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
struct module *me)
{
struct mod_arch_syminfo *info;
Elf_Addr loc, val;
int r_type, r_sym;
/* This is where to make the change */
loc = base + rela->r_offset;
/* This is the symbol it is referring to. Note that all
undefined symbols have been resolved. */
r_sym = ELF_R_SYM(rela->r_info);
r_type = ELF_R_TYPE(rela->r_info);
info = me->arch.syminfo + r_sym;
val = symtab[r_sym].st_value;
switch (r_type) {
case R_390_8: /* Direct 8 bit. */
case R_390_12: /* Direct 12 bit. */
case R_390_16: /* Direct 16 bit. */
case R_390_20: /* Direct 20 bit. */
case R_390_32: /* Direct 32 bit. */
case R_390_64: /* Direct 64 bit. */
val += rela->r_addend;
if (r_type == R_390_8)
*(unsigned char *) loc = val;
else if (r_type == R_390_12)
*(unsigned short *) loc = (val & 0xfff) |
(*(unsigned short *) loc & 0xf000);
else if (r_type == R_390_16)
*(unsigned short *) loc = val;
else if (r_type == R_390_20)
*(unsigned int *) loc =
(*(unsigned int *) loc & 0xf00000ff) |
(val & 0xfff) << 16 | (val & 0xff000) >> 4;
else if (r_type == R_390_32)
*(unsigned int *) loc = val;
else if (r_type == R_390_64)
*(unsigned long *) loc = val;
break;
case R_390_PC16: /* PC relative 16 bit. */
case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
case R_390_PC32: /* PC relative 32 bit. */
case R_390_PC64: /* PC relative 64 bit. */
val += rela->r_addend - loc;
if (r_type == R_390_PC16)
*(unsigned short *) loc = val;
else if (r_type == R_390_PC16DBL)
*(unsigned short *) loc = val >> 1;
else if (r_type == R_390_PC32DBL)
*(unsigned int *) loc = val >> 1;
else if (r_type == R_390_PC32)
*(unsigned int *) loc = val;
else if (r_type == R_390_PC64)
*(unsigned long *) loc = val;
break;
case R_390_GOT12: /* 12 bit GOT offset. */
case R_390_GOT16: /* 16 bit GOT offset. */
case R_390_GOT20: /* 20 bit GOT offset. */
case R_390_GOT32: /* 32 bit GOT offset. */
case R_390_GOT64: /* 64 bit GOT offset. */
case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
if (info->got_initialized == 0) {
Elf_Addr *gotent;
gotent = me->module_core + me->arch.got_offset +
info->got_offset;
*gotent = val;
info->got_initialized = 1;
}
val = info->got_offset + rela->r_addend;
if (r_type == R_390_GOT12 ||
r_type == R_390_GOTPLT12)
*(unsigned short *) loc = (val & 0xfff) |
(*(unsigned short *) loc & 0xf000);
else if (r_type == R_390_GOT16 ||
r_type == R_390_GOTPLT16)
*(unsigned short *) loc = val;
else if (r_type == R_390_GOT20 ||
r_type == R_390_GOTPLT20)
*(unsigned int *) loc =
(*(unsigned int *) loc & 0xf00000ff) |
(val & 0xfff) << 16 | (val & 0xff000) >> 4;
else if (r_type == R_390_GOT32 ||
r_type == R_390_GOTPLT32)
*(unsigned int *) loc = val;
else if (r_type == R_390_GOTENT ||
r_type == R_390_GOTPLTENT)
*(unsigned int *) loc =
(val + (Elf_Addr) me->module_core - loc) >> 1;
else if (r_type == R_390_GOT64 ||
r_type == R_390_GOTPLT64)
*(unsigned long *) loc = val;
break;
case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
case R_390_PLT32: /* 32 bit PC relative PLT address. */
case R_390_PLT64: /* 64 bit PC relative PLT address. */
case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
if (info->plt_initialized == 0) {
unsigned int *ip;
ip = me->module_core + me->arch.plt_offset +
info->plt_offset;
#ifndef CONFIG_64BIT
ip[0] = 0x0d105810; /* basr 1,0; l 1,6(1); br 1 */
ip[1] = 0x100607f1;
ip[2] = val;
#else /* CONFIG_64BIT */
ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */
ip[1] = 0x100a0004;
ip[2] = 0x07f10000;
ip[3] = (unsigned int) (val >> 32);
ip[4] = (unsigned int) val;
#endif /* CONFIG_64BIT */
info->plt_initialized = 1;
}
if (r_type == R_390_PLTOFF16 ||
r_type == R_390_PLTOFF32 ||
r_type == R_390_PLTOFF64)
val = me->arch.plt_offset - me->arch.got_offset +
info->plt_offset + rela->r_addend;
else {
if (!((r_type == R_390_PLT16DBL &&
val - loc + 0xffffUL < 0x1ffffeUL) ||
(r_type == R_390_PLT32DBL &&
val - loc + 0xffffffffULL < 0x1fffffffeULL)))
val = (Elf_Addr) me->module_core +
me->arch.plt_offset +
info->plt_offset;
val += rela->r_addend - loc;
}
if (r_type == R_390_PLT16DBL)
*(unsigned short *) loc = val >> 1;
else if (r_type == R_390_PLTOFF16)
*(unsigned short *) loc = val;
else if (r_type == R_390_PLT32DBL)
*(unsigned int *) loc = val >> 1;
else if (r_type == R_390_PLT32 ||
r_type == R_390_PLTOFF32)
*(unsigned int *) loc = val;
else if (r_type == R_390_PLT64 ||
r_type == R_390_PLTOFF64)
*(unsigned long *) loc = val;
break;
case R_390_GOTOFF16: /* 16 bit offset to GOT. */
case R_390_GOTOFF32: /* 32 bit offset to GOT. */
case R_390_GOTOFF64: /* 64 bit offset to GOT. */
val = val + rela->r_addend -
((Elf_Addr) me->module_core + me->arch.got_offset);
if (r_type == R_390_GOTOFF16)
*(unsigned short *) loc = val;
else if (r_type == R_390_GOTOFF32)
*(unsigned int *) loc = val;
else if (r_type == R_390_GOTOFF64)
*(unsigned long *) loc = val;
break;
case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */
val = (Elf_Addr) me->module_core + me->arch.got_offset +
rela->r_addend - loc;
if (r_type == R_390_GOTPC)
*(unsigned int *) loc = val;
else if (r_type == R_390_GOTPCDBL)
*(unsigned int *) loc = val >> 1;
break;
case R_390_COPY:
case R_390_GLOB_DAT: /* Create GOT entry. */
case R_390_JMP_SLOT: /* Create PLT entry. */
case R_390_RELATIVE: /* Adjust by program base. */
/* Only needed if we want to support loading of
modules linked with -shared. */
break;
default:
printk(KERN_ERR "module %s: Unknown relocation: %u\n",
me->name, r_type);
return -ENOEXEC;
}
return 0;
}
int
apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec,
struct module *me)
{
Elf_Addr base;
Elf_Sym *symtab;
Elf_Rela *rela;
unsigned long i, n;
int rc;
DEBUGP("Applying relocate section %u to %u\n",
relsec, sechdrs[relsec].sh_info);
base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
for (i = 0; i < n; i++, rela++) {
rc = apply_rela(rela, base, symtab, me);
if (rc)
return rc;
}
return 0;
}
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
vfree(me->arch.syminfo);
me->arch.syminfo = NULL;
return module_bug_finalize(hdr, sechdrs, me);
}
void module_arch_cleanup(struct module *mod)
{
module_bug_cleanup(mod);
}
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