CVE-2017-9207 (published 2017-05-23T04:29Z)

The iw_get_ui16be function in imagew-util.c:422:24 in libimageworsener.a in ImageWorsener 1.3.1 allows remote attackers to cause a denial of service (heap-based buffer over-read) via a crafted image, related to imagew-jpeg.c.

Severity: MEDIUM
CVSS v2 base score: 4.3 (AV:N/AC:M/Au:N/C:N/I:N/A:P)
CVSS v3 base score: 6.5, MEDIUM (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: CWE-125
cwe_name: Out-of-bounds Read
description: The product reads data past the end, or before the beginning, of the intended buffer.
extended_description: 
            
            
             
			 
         
         

Fix information:
repo_url: https://github.com/jsummers/imageworsener
commit_details: repo_url: https://github.com/jsummers/imageworsener
author: Jason Summers
author_date: 2017-05-14 12:37:43-04:00
msg: Fixed invalid memory access bugs when decoding JPEG Exif data

Fixes issues #22, #23, #24, #25
repository: repo_url: https://github.com/jsummers/imageworsener
repo_name: jsummers/imageworsener
description: A utility for processing PNG, JPEG, BMP, and WebP images. Features include resize/resample, dither, grayscale, apply background color, subpixel rendering.
repo_language: C
owner: jsummers
file_changes: filename: imagew-jpeg.c
change_type: ModificationType.MODIFY
diff: @@ -58,6 +58,18 @@ struct iw_exif_state {
 	size_t d_len;
 };
 
+static unsigned int get_exif_ui16(struct iw_exif_state *e, unsigned int pos)
+{
+	if(e->d_len<2 || pos>e->d_len-2) return 0;
+	return iw_get_ui16_e(&e->d[pos], e->endian);
+}
+
+static unsigned int get_exif_ui32(struct iw_exif_state *e, unsigned int pos)
+{
+	if(e->d_len<4 || pos>e->d_len-4) return 0;
+	return iw_get_ui32_e(&e->d[pos], e->endian);
+}
+
 // Try to read an Exif tag into an integer.
 // Returns zero on failure.
 static int get_exif_tag_int_value(struct iw_exif_state *e, unsigned int tag_pos,
@@ -66,17 +78,17 @@ static int get_exif_tag_int_value(struct iw_exif_state *e, unsigned int tag_pos,
 	unsigned int field_type;
 	unsigned int value_count;
 
-	field_type = iw_get_ui16_e(&e->d[tag_pos+2],e->endian);
-	value_count = iw_get_ui32_e(&e->d[tag_pos+4],e->endian);
+	field_type = get_exif_ui16(e, tag_pos+2);
+	value_count = get_exif_ui32(e, tag_pos+4);
 
 	if(value_count!=1) return 0;
 
 	if(field_type==3) { // SHORT (uint16)
-		*pv = iw_get_ui16_e(&e->d[tag_pos+8],e->endian);
+		*pv = get_exif_ui16(e, tag_pos+8);
 		return 1;
 	}
 	else if(field_type==4) { // LONG (uint32)
-		*pv = iw_get_ui32_e(&e->d[tag_pos+8],e->endian);
+		*pv = get_exif_ui32(e, tag_pos+8);
 		return 1;
 	}
 
@@ -93,8 +105,8 @@ static int get_exif_tag_dbl_value(struct iw_exif_state *e, unsigned int tag_pos,
 	unsigned int value_pos;
 	unsigned int numer, denom;
 
-	field_type = iw_get_ui16_e(&e->d[tag_pos+2],e->endian);
-	value_count = iw_get_ui32_e(&e->d[tag_pos+4],e->endian);
+	field_type = get_exif_ui16(e, tag_pos+2);
+	value_count = get_exif_ui32(e, tag_pos+4);
 
 	if(value_count!=1) return 0;
 
@@ -103,12 +115,12 @@ static int get_exif_tag_dbl_value(struct iw_exif_state *e, unsigned int tag_pos,
 	// A rational is 8 bytes. Since 8>4, it is stored indirectly. First, read
 	// the location where it is stored.
 
-	value_pos = iw_get_ui32_e(&e->d[tag_pos+8],e->endian);
+	value_pos = get_exif_ui32(e, tag_pos+8);
 	if(value_pos > e->d_len-8) return 0;
 
 	// Read the actual value.
-	numer = iw_get_ui32_e(&e->d[value_pos  ],e->endian);
-	denom = iw_get_ui32_e(&e->d[value_pos+4],e->endian);
+	numer = get_exif_ui32(e, value_pos);
+	denom = get_exif_ui32(e, value_pos+4);
 	if(denom==0) return 0;
 
 	*pv = ((double)numer)/denom;
@@ -125,15 +137,15 @@ static void iwjpeg_scan_exif_ifd(struct iwjpegrcontext *rctx,
 	unsigned int v;
 	double v_dbl;
 
-	if(ifd<8 || ifd>e->d_len-18) return;
+	if(ifd<8 || e->d_len<18 || ifd>e->d_len-18) return;
 
-	tag_count = iw_get_ui16_e(&e->d[ifd],e->endian);
+	tag_count = get_exif_ui16(e, ifd);
 	if(tag_count>1000) return; // Sanity check.
 
 	for(i=0;i<tag_count;i++) {
 		tag_pos = ifd+2+i*12;
 		if(tag_pos+12 > e->d_len) return; // Avoid overruns.
-		tag_id = iw_get_ui16_e(&e->d[tag_pos],e->endian);
+		tag_id = get_exif_ui16(e, tag_pos);
 
 		switch(tag_id) {
 		case 274: // 274 = Orientation
@@ -177,7 +189,7 @@ static void iwjpeg_scan_exif(struct iwjpegrcontext *rctx,
 
 	e.endian = d[0]=='I' ? IW_ENDIAN_LITTLE : IW_ENDIAN_BIG;
 
-	ifd = iw_get_ui32_e(&d[4],e.endian);
+	ifd = get_exif_ui32(&e, 4);
 
 	iwjpeg_scan_exif_ifd(rctx,&e,ifd);
 }

programming_language: C