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Make TIFF parsing a bit safer

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At least on 64-bit systems, 32-bit may still have holes.
This commit is contained in:
Přemysl Eric Janouch 2023-05-28 03:22:36 +02:00
parent df7c7b9f6b
commit 902eaf5a01
Signed by: p
GPG Key ID: A0420B94F92B9493
3 changed files with 23 additions and 16 deletions
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9
fiv-io.c
View File

@ -1844,11 +1844,10 @@ tiff_ep_find_jpeg_evaluate(const struct tiffer *T, struct tiff_ep_jpeg *out)
}
int64_t ipointer = 0, ilength = 0;
if (!tiffer_find_integer(T, tag_pointer, &ipointer) ||
!tiffer_find_integer(T, tag_length, &ilength) ||
ipointer <= 0 || ilength <= 0 ||
(uint64_t) ilength > SIZE_MAX ||
ipointer + ilength > (T->end - T->begin))
if (!tiffer_find_integer(T, tag_pointer, &ipointer) || ipointer <= 0 ||
!tiffer_find_integer(T, tag_length, &ilength) || ilength <= 0 ||
ipointer > T->end - T->begin ||
T->end - T->begin - ipointer < ilength)
return;
// Note that to get the largest JPEG,

15
tiffer.h
View File

@ -15,9 +15,10 @@
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <stdbool.h>
// --- Utilities ---------------------------------------------------------------
@ -85,7 +86,7 @@ struct tiffer {
static bool
tiffer_u32(struct tiffer *self, uint32_t *u)
{
if (self->p < self->begin || self->p + 4 > self->end)
if (self->end - self->p < 4)
return false;
*u = self->un->u32(self->p);
@ -96,7 +97,7 @@ tiffer_u32(struct tiffer *self, uint32_t *u)
static bool
tiffer_u16(struct tiffer *self, uint16_t *u)
{
if (self->p < self->begin || self->p + 2 > self->end)
if (self->end - self->p < 2)
return false;
*u = self->un->u16(self->p);
@ -160,6 +161,9 @@ static bool
tiffer_subifd(
const struct tiffer *self, uint32_t offset, struct tiffer *subreader)
{
if (self->end - self->begin < offset)
return false;
*subreader = *self;
subreader->p = subreader->begin + offset;
return tiffer_u16(subreader, &subreader->remaining_fields);
@ -323,14 +327,15 @@ tiffer_next_entry(struct tiffer *self, struct tiffer_entry *entry)
if (values_size <= sizeof offset) {
entry->p = self->p;
self->p += sizeof offset;
} else if (tiffer_u32(self, &offset)) {
} else if (tiffer_u32(self, &offset) && self->end - self->begin >= offset) {
entry->p = self->begin + offset;
} else {
return false;
}
// All entries are pre-checked not to overflow.
if (entry->p + values_size > self->end)
if (values_size > PTRDIFF_MAX ||
self->end - entry->p < (ptrdiff_t) values_size)
return false;
// Setting it at the end may provide an indication while debugging.

15
tools/info.h
View File

@ -92,8 +92,8 @@ static jv parse_jpeg(jv o, const uint8_t *p, size_t len);
static jv parse_exif_ifd(struct tiffer *T, const struct tiff_entry *info);
static bool
parse_exif_subifds_entry(struct tiffer *T, const struct tiffer_entry *entry,
struct tiffer *subT)
parse_exif_subifds_entry(const struct tiffer *T,
const struct tiffer_entry *entry, struct tiffer *subT)
{
int64_t offset = 0;
return tiffer_integer(T, entry, &offset) &&
@ -101,7 +101,7 @@ parse_exif_subifds_entry(struct tiffer *T, const struct tiffer_entry *entry,
}
static jv
parse_exif_subifds(struct tiffer *T, struct tiffer_entry *entry,
parse_exif_subifds(const struct tiffer *T, struct tiffer_entry *entry,
struct tiff_entry *info)
{
struct tiffer subT = {};
@ -173,7 +173,7 @@ parse_exif_extract_sole_array_element(jv a)
}
static jv
parse_exif_entry(jv o, struct tiffer *T, struct tiffer_entry *entry,
parse_exif_entry(jv o, const struct tiffer *T, struct tiffer_entry *entry,
const struct tiff_entry *info)
{
static struct tiff_entry empty[] = {{}};
@ -679,7 +679,7 @@ static struct tiff_entry mpf_entries[] = {
};
static uint32_t
parse_mpf_mpentry(jv *a, const uint8_t *p, struct tiffer *T)
parse_mpf_mpentry(jv *a, const uint8_t *p, const struct tiffer *T)
{
uint32_t attrs = T->un->u32(p);
uint32_t offset = T->un->u32(p + 8);
@ -725,7 +725,7 @@ parse_mpf_mpentry(jv *a, const uint8_t *p, struct tiffer *T)
}
static jv
parse_mpf_index_entry(jv o, const uint8_t ***offsets, struct tiffer *T,
parse_mpf_index_entry(jv o, const uint8_t ***offsets, const struct tiffer *T,
struct tiffer_entry *entry)
{
// 5.2.3.3. MP Entry
@ -738,6 +738,9 @@ parse_mpf_index_entry(jv o, const uint8_t ***offsets, struct tiffer *T,
jv a = jv_array_sized(count);
const uint8_t **out = *offsets = calloc(sizeof *out, count + 1);
for (uint32_t i = 0; i < count; i++) {
// 5.2.3.3.3. Individual Image Data Offset
// XXX: We might want to warn about out-of-bounds pointers,
// however T->end is for the MPF segment and ends too early.
uint32_t offset = parse_mpf_mpentry(&a, entry->p + i * 16, T);
if (offset)
*out++ = T->begin + offset;