https://github.com/libexif/libexif/commit/75aa73267fdb1e0ebfbc00369e7312bac43d0566.patch

From 75aa73267fdb1e0ebfbc00369e7312bac43d0566 Mon Sep 17 00:00:00 2001

From: Marcus Meissner <meissner@suse.de>

Date: Sat, 18 Jan 2020 09:29:42 +0100

Subject: [PATCH] fix CVE-2019-9278

avoid the use of unsafe integer overflow checking constructs (unsigned integer operations cannot overflow, so "u1 + u2 > u1" can be optimized away)

check for the actual sizes, which should also handle the overflows

document other places google patched, but do not seem relevant due to other restrictions

fixes https://github.com/libexif/libexif/issues/26

---

 libexif/exif-data.c | 28 ++++++++++++++++++----------

 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git libexif/exif-data.c libexif/exif-data.c

index a6f9c94..6332cd1 100644

--- libexif/exif-data.c

+++ libexif/exif-data.c

@@ -192,9 +192,15 @@ exif_data_load_data_entry (ExifData *data, ExifEntry *entry,

 		doff = offset + 8;

 	/* Sanity checks */

-	if ((doff + s < doff) || (doff + s < s) || (doff + s > size)) {

+	if (doff >= size) {

 		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",

-				  "Tag data past end of buffer (%u > %u)", doff+s, size);	

+				  "Tag starts past end of buffer (%u > %u)", doff, size);

+		return 0;

+	}

+

+	if (s > size - doff) {

+		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",

+				  "Tag data goes past end of buffer (%u > %u)", doff+s, size);

 		return 0;

 	}

@@ -315,13 +321,14 @@ exif_data_load_data_thumbnail (ExifData *data, const unsigned char *d,

 			       unsigned int ds, ExifLong o, ExifLong s)

 {

 	/* Sanity checks */

-	if ((o + s < o) || (o + s < s) || (o + s > ds) || (o > ds)) {

-		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",

-			  "Bogus thumbnail offset (%u) or size (%u).",

-			  o, s);

+	if (o >= ds) {

+		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", "Bogus thumbnail offset (%u).", o);

+		return;

+	}

+	if (s > ds - o) {

+		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", "Bogus thumbnail size (%u), max would be %u.", s, ds-o);

 		return;

 	}

-

 	if (data->data) 

 		exif_mem_free (data->priv->mem, data->data);

 	if (!(data->data = exif_data_alloc (data, s))) {

@@ -947,7 +954,7 @@ exif_data_load_data (ExifData *data, const unsigned char *d_orig,

 	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", 

 		  "IFD 0 at %i.", (int) offset);

-	/* Sanity check the offset, being careful about overflow */

+	/* ds is restricted to 16 bit above, so offset is restricted too, and offset+8 should not overflow. */

 	if (offset > ds || offset + 6 + 2 > ds)

 		return;

@@ -956,6 +963,7 @@ exif_data_load_data (ExifData *data, const unsigned char *d_orig,

 	/* IFD 1 offset */

 	n = exif_get_short (d + 6 + offset, data->priv->order);

+	/* offset < 2<<16, n is 16 bit at most, so this op will not overflow */

 	if (offset + 6 + 2 + 12 * n + 4 > ds)

 		return;

@@ -964,8 +972,8 @@ exif_data_load_data (ExifData *data, const unsigned char *d_orig,

 		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",

 			  "IFD 1 at %i.", (int) offset);

-		/* Sanity check. */

-		if (offset > ds || offset + 6 > ds) {

+		/* Sanity check. ds is ensured to be above 6 above, offset is 16bit */

+		if (offset > ds - 6) {

 			exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA,

 				  "ExifData", "Bogus offset of IFD1.");

 		} else {

https://github.com/libexif/libexif/commit/f9bb9f263fb00f0603ecbefa8957cad24168cbff.patch

From f9bb9f263fb00f0603ecbefa8957cad24168cbff Mon Sep 17 00:00:00 2001

From: Dan Fandrich <dan@coneharvesters.com>

Date: Wed, 4 Jul 2018 11:06:09 +0200

Subject: [PATCH] Fix a buffer read overflow in exif_entry_get_value

While parsing EXIF_TAG_FOCAL_LENGTH it was possible to read 8 bytes past

the end of a heap buffer. This was detected by the OSS Fuzz project.

Patch from Google.

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=7344 and

https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14543

---

 libexif/exif-entry.c | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git libexif/exif-entry.c libexif/exif-entry.c

index 61260d3..a224ac2 100644

--- libexif/exif-entry.c

+++ libexif/exif-entry.c

@@ -1040,12 +1040,12 @@ exif_entry_get_value (ExifEntry *e, char *val, unsigned int maxlen)

 		d = 0.;

 		entry = exif_content_get_entry (

 			e->parent->parent->ifd[EXIF_IFD_0], EXIF_TAG_MAKE);

-		if (entry && entry->data &&

+		if (entry && entry->data && entry->size >= 7 &&

 		    !strncmp ((char *)entry->data, "Minolta", 7)) {

 			entry = exif_content_get_entry (

 					e->parent->parent->ifd[EXIF_IFD_0],

 					EXIF_TAG_MODEL);

-			if (entry && entry->data) {

+			if (entry && entry->data && entry->size >= 8) {

 				if (!strncmp ((char *)entry->data, "DiMAGE 7", 8))

 					d = 3.9;

 				else if (!strncmp ((char *)entry->data, "DiMAGE 5", 8))

https://github.com/libexif/libexif/commit/a0c04d9cb6ab0c41a6458def9f892754e84160a0.patch

From a0c04d9cb6ab0c41a6458def9f892754e84160a0 Mon Sep 17 00:00:00 2001

From: Marcus Meissner <marcus@jet.franken.de>

Date: Sat, 15 Jun 2019 18:40:48 +0200

Subject: [PATCH] fixed a buffer overread (OSS-Fuzz)

 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=8884

---

 libexif/olympus/exif-mnote-data-olympus.c | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git libexif/olympus/exif-mnote-data-olympus.c libexif/olympus/exif-mnote-data-olympus.c

index dac7f5b..669e4ec 100644

--- libexif/olympus/exif-mnote-data-olympus.c

+++ libexif/olympus/exif-mnote-data-olympus.c

@@ -344,7 +344,7 @@ exif_mnote_data_olympus_load (ExifMnoteData *en,

 	case nikonV2:

 		o2 += 6;

-		if (o2 >= buf_size) return;

+		if (o2 + 8 >= buf_size) return;

 		exif_log (en->log, EXIF_LOG_CODE_DEBUG, "ExifMnoteDataOlympus",

 			"Parsing Nikon maker note v2 (0x%02x, %02x, %02x, "

 			"%02x, %02x, %02x, %02x, %02x)...",