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Improve TIFF handling within tools 

Nikon NEFs violate TIFF Tech Note 1, and it is easy to detect.

Also guard against more pointer overflows, and fix a temporary array
being used outside of its scope (found by a compiler).
This commit is contained in:
Přemysl Eric Janouch 2023-05-22 20:48:59 +02:00
parent 544722f8e0
commit dba728e0c4
Signed by: p
GPG Key ID: A0420B94F92B9493
1 changed files with 27 additions and 11 deletions
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38
tools/info.h
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@ -96,8 +96,9 @@ struct tiffer {
static bool
tiffer_u32(struct tiffer *self, uint32_t *u)
{
if (self->p + 4 > self->end)
if (self->p < self->begin || self->p + 4 > self->end)
return false;
*u = self->un->u32(self->p);
self->p += 4;
return true;
@ -106,8 +107,9 @@ tiffer_u32(struct tiffer *self, uint32_t *u)
static bool
tiffer_u16(struct tiffer *self, uint16_t *u)
{
if (self->p + 2 > self->end)
if (self->p < self->begin || self->p + 2 > self->end)
return false;
*u = self->un->u16(self->p);
self->p += 2;
return true;
@ -403,22 +405,35 @@ add_error(jv o, const char *message)
static jv parse_exif_ifd(struct tiffer *T, const struct tiff_entry *info);
static jv
parse_exif_subifds(struct tiffer *T, const struct tiffer_entry *entry,
struct tiff_entry *info)
static bool
parse_exif_subifds_entry(struct tiffer *T, const struct tiffer_entry *entry,
struct tiffer *subT)
{
int64_t offset = 0;
return tiffer_integer(T, entry, &offset) &&
offset >= 0 && offset <= UINT32_MAX && tiffer_subifd(T, offset, subT);
}
static jv
parse_exif_subifds(struct tiffer *T, struct tiffer_entry *entry,
struct tiff_entry *info)
{
struct tiffer subT = {};
if (!tiffer_integer(T, entry, &offset) ||
offset < 0 || offset > UINT32_MAX || !tiffer_subifd(T, offset, &subT))
if (!parse_exif_subifds_entry(T, entry, &subT))
return jv_null();
// The chain should correspond to the values in the entry
// (TIFF Technical Note 1), we are not going to verify it.
// Note that Nikon NEFs do not follow this rule.
jv a = jv_array();
do a = jv_array_append(a, parse_exif_ifd(&subT, info));
while (tiffer_next_ifd(&subT));
// The chain should correspond to the values in the entry (see TIFF
// Technical Note 1: "the NextIFD value of Child #1 must point to Child #2,
// and so on"), but at least some Nikon NEFs do not follow this rule.
if (jv_array_length(jv_copy(a)) == 1) {
while (tiffer_next_value(entry) &&
parse_exif_subifds_entry(T, entry, &subT))
a = jv_array_append(a, parse_exif_ifd(&subT, info));
}
return a;
}
@ -475,8 +490,9 @@ static jv
parse_exif_entry(jv o, struct tiffer *T, struct tiffer_entry *entry,
const struct tiff_entry *info)
{
static struct tiff_entry empty[] = {{}};
if (!info)
info = (struct tiff_entry[]) {{}};
info = empty;
for (; info->name; info++)
if (info->tag == entry->tag)