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loader: Check access size when calling rom_ptr() to avoid crashes

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The rom_ptr() function allows direct access to the ROM blobs that we
load during startup. However, there are currently no checks for the
size of the accesses, so it's currently possible to crash QEMU for
example with:

$ echo "Insane in the mainframe" > /tmp/test.txt
$ s390x-softmmu/qemu-system-s390x -kernel /tmp/test.txt -append xyz
Segmentation fault (core dumped)
$ s390x-softmmu/qemu-system-s390x -kernel /tmp/test.txt -initrd /tmp/test.txt
Segmentation fault (core dumped)
$ echo -n HdrS > /tmp/hdr.txt
$ sparc64-softmmu/qemu-system-sparc64 -kernel /tmp/hdr.txt -initrd /tmp/hdr.txt
Segmentation fault (core dumped)

We need a possibility to check the size of the ROM area that we want
to access, thus let's add a size parameter to the rom_ptr() function
to avoid these problems.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1530005740-25254-1-git-send-email-thuth@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
Thomas Huth 2018-06-26 11:35:40 +02:00 committed by Cornelia Huck
parent 76ed4b18de
commit 0f0f8b611e
7 changed files with 27 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
hw/core/loader.c
View File

@ -191,7 +191,7 @@ void pstrcpy_targphys(const char *name, hwaddr dest, int buf_size,
rom_add_blob_fixed(name, source, (nulp - source) + 1, dest);
} else {
rom_add_blob_fixed(name, source, buf_size, dest);
ptr = rom_ptr(dest + buf_size - 1);
ptr = rom_ptr(dest + buf_size - 1, sizeof(*ptr));
*ptr = 0;
}
}
@ -1165,7 +1165,7 @@ void rom_reset_order_override(void)
fw_cfg_reset_order_override(fw_cfg);
}
static Rom *find_rom(hwaddr addr)
static Rom *find_rom(hwaddr addr, size_t size)
{
Rom *rom;
@ -1179,7 +1179,7 @@ static Rom *find_rom(hwaddr addr)
if (rom->addr > addr) {
continue;
}
if (rom->addr + rom->romsize < addr) {
if (rom->addr + rom->romsize < addr + size) {
continue;
}
return rom;
@ -1249,11 +1249,11 @@ int rom_copy(uint8_t *dest, hwaddr addr, size_t size)
return (d + l) - dest;
}
void *rom_ptr(hwaddr addr)
void *rom_ptr(hwaddr addr, size_t size)
{
Rom *rom;
rom = find_rom(addr);
rom = find_rom(addr, size);
if (!rom || !rom->data)
return NULL;
return rom->data + (addr - rom->addr);

6
hw/mips/mips_malta.c
View File

@ -1133,11 +1133,13 @@ void mips_malta_init(MachineState *machine)
a neat trick which allows bi-endian firmware. */
#ifndef TARGET_WORDS_BIGENDIAN
{
uint32_t *end, *addr = rom_ptr(FLASH_ADDRESS);
uint32_t *end, *addr;
const size_t swapsize = MIN(bios_size, 0x3e0000);
addr = rom_ptr(FLASH_ADDRESS, swapsize);
if (!addr) {
addr = memory_region_get_ram_ptr(bios);
}
end = (void *)addr + MIN(bios_size, 0x3e0000);
end = (void *)addr + swapsize;
while (addr < end) {
bswap32s(addr);
addr++;

18
hw/s390x/ipl.c
View File

@ -33,7 +33,6 @@
#define KERN_PARM_AREA 0x010480UL
#define INITRD_START 0x800000UL
#define INITRD_PARM_START 0x010408UL
#define INITRD_PARM_SIZE 0x010410UL
#define PARMFILE_START 0x001000UL
#define ZIPL_IMAGE_START 0x009000UL
#define IPL_PSW_MASK (PSW_MASK_32 | PSW_MASK_64)
@ -165,12 +164,12 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
goto error;
}
/* if this is Linux use KERN_IMAGE_START */
magic = rom_ptr(LINUX_MAGIC_ADDR);
magic = rom_ptr(LINUX_MAGIC_ADDR, 6);
if (magic && !memcmp(magic, "S390EP", 6)) {
pentry = KERN_IMAGE_START;
} else {
/* if not Linux load the address of the (short) IPL PSW */
ipl_psw = rom_ptr(4);
ipl_psw = rom_ptr(4, 4);
if (ipl_psw) {
pentry = be32_to_cpu(*ipl_psw) & 0x7fffffffUL;
} else {
@ -186,9 +185,12 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
* loader) and it won't work. For this case we force it to 0x10000, too.
*/
if (pentry == KERN_IMAGE_START || pentry == 0x800) {
char *parm_area = rom_ptr(KERN_PARM_AREA, strlen(ipl->cmdline) + 1);
ipl->start_addr = KERN_IMAGE_START;
/* Overwrite parameters in the kernel image, which are "rom" */
strcpy(rom_ptr(KERN_PARM_AREA), ipl->cmdline);
if (parm_area) {
strcpy(parm_area, ipl->cmdline);
}
} else {
ipl->start_addr = pentry;
}
@ -196,6 +198,7 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
if (ipl->initrd) {
ram_addr_t initrd_offset;
int initrd_size;
uint64_t *romptr;
initrd_offset = INITRD_START;
while (kernel_size + 0x100000 > initrd_offset) {
@ -212,8 +215,11 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
* we have to overwrite values in the kernel image,
* which are "rom"
*/
stq_p(rom_ptr(INITRD_PARM_START), initrd_offset);
stq_p(rom_ptr(INITRD_PARM_SIZE), initrd_size);
romptr = rom_ptr(INITRD_PARM_START, 16);
if (romptr) {
stq_p(romptr, initrd_offset);
stq_p(romptr + 1, initrd_size);
}
}
}
/*

4
hw/sparc/sun4m.c
View File

@ -272,8 +272,8 @@ static unsigned long sun4m_load_kernel(const char *kernel_filename,
}
if (initrd_size > 0) {
for (i = 0; i < 64 * TARGET_PAGE_SIZE; i += TARGET_PAGE_SIZE) {
ptr = rom_ptr(KERNEL_LOAD_ADDR + i);
if (ldl_p(ptr) == 0x48647253) { // HdrS
ptr = rom_ptr(KERNEL_LOAD_ADDR + i, 24);
if (ptr && ldl_p(ptr) == 0x48647253) { /* HdrS */
stl_p(ptr + 16, INITRD_LOAD_ADDR);
stl_p(ptr + 20, initrd_size);
break;

4
hw/sparc64/sun4u.c
View File

@ -186,8 +186,8 @@ static uint64_t sun4u_load_kernel(const char *kernel_filename,
}
if (*initrd_size > 0) {
for (i = 0; i < 64 * TARGET_PAGE_SIZE; i += TARGET_PAGE_SIZE) {
ptr = rom_ptr(*kernel_addr + i);
if (ldl_p(ptr + 8) == 0x48647253) { /* HdrS */
ptr = rom_ptr(*kernel_addr + i, 32);
if (ptr && ldl_p(ptr + 8) == 0x48647253) { /* HdrS */
stl_p(ptr + 24, *initrd_addr + *kernel_addr);
stl_p(ptr + 28, *initrd_size);
break;

2
include/hw/loader.h
View File

@ -226,7 +226,7 @@ void rom_set_fw(FWCfgState *f);
void rom_set_order_override(int order);
void rom_reset_order_override(void);
int rom_copy(uint8_t *dest, hwaddr addr, size_t size);
void *rom_ptr(hwaddr addr);
void *rom_ptr(hwaddr addr, size_t size);
void hmp_info_roms(Monitor *mon, const QDict *qdict);
#define rom_add_file_fixed(_f, _a, _i) \

2
target/arm/cpu.c
View File

@ -239,7 +239,7 @@ static void arm_cpu_reset(CPUState *s)
/* Load the initial SP and PC from offset 0 and 4 in the vector table */
vecbase = env->v7m.vecbase[env->v7m.secure];
rom = rom_ptr(vecbase);
rom = rom_ptr(vecbase, 8);
if (rom) {
/* Address zero is covered by ROM which hasn't yet been
* copied into physical memory.