From 52603840b1c5d923cc998335fb651a53d42a036c Mon Sep 17 00:00:00 2001

From: Alan Coopersmith <alan.coopersmith@oracle.com>

Date: Sat, 7 Jan 2023 12:44:28 -0800

Subject: [PATCH libXpm 2/5] Fix CVE-2022-44617: Runaway loop with width of 0

 and enormous height

When reading XPM images from a file with libXpm 3.5.14 or older, if a

image has a width of 0 and a very large height, the ParsePixels() function

will loop over the entire height calling getc() and ungetc() repeatedly,

or in some circumstances, may loop seemingly forever, which may cause a

denial of service to the calling program when given a small crafted XPM

file to parse.

Closes: #2

Reported-by: Martin Ettl <ettl.martin78@googlemail.com>

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

---

 src/data.c  | 20 ++++++++++++++------

 src/parse.c | 31 +++++++++++++++++++++++++++----

 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/src/data.c b/src/data.c

index bfad4ff..7524e65 100644

--- a/src/data.c

+++ b/src/data.c

@@ -195,19 +195,23 @@ xpmNextString(xpmData *data)

 	register char c;

 	/* get to the end of the current string */

-	if (data->Eos)

-	    while ((c = *data->cptr++) && c != data->Eos);

+	if (data->Eos) {

+	    while ((c = *data->cptr++) && c != data->Eos && c != '\0');

+

+	    if (c == '\0')

+		return XpmFileInvalid;

+	}

 	/*

 	 * then get to the beginning of the next string looking for possible

 	 * comment

 	 */

 	if (data->Bos) {

-	    while ((c = *data->cptr++) && c != data->Bos)

+	    while ((c = *data->cptr++) && c != data->Bos && c != '\0')

 		if (data->Bcmt && c == data->Bcmt[0])

 		    ParseComment(data);

 	} else if (data->Bcmt) {	/* XPM2 natural */

-	    while ((c = *data->cptr++) == data->Bcmt[0])

+	    while (((c = *data->cptr++) == data->Bcmt[0]) && c != '\0')

 		ParseComment(data);

 	    data->cptr--;

 	}

@@ -216,9 +220,13 @@ xpmNextString(xpmData *data)

 	FILE *file = data->stream.file;

 	/* get to the end of the current string */

-	if (data->Eos)

+	if (data->Eos) {

 	    while ((c = Getc(data, file)) != data->Eos && c != EOF);

+	    if (c == EOF)

+		return XpmFileInvalid;

+	}

+

 	/*

 	 * then get to the beginning of the next string looking for possible

 	 * comment

@@ -234,7 +242,7 @@ xpmNextString(xpmData *data)

 	    Ungetc(data, c, file);

 	}

     }

-    return 0;

+    return XpmSuccess;

 }

diff --git a/src/parse.c b/src/parse.c

index c19209c..e97d771 100644

--- a/src/parse.c

+++ b/src/parse.c

@@ -391,6 +391,13 @@ ParsePixels(

 {

     unsigned int *iptr, *iptr2 = NULL; /* found by Egbert Eich */

     unsigned int a, x, y;

+    int ErrorStatus;

+

+    if ((width == 0) && (height != 0))

+	return (XpmFileInvalid);

+

+    if ((height == 0) && (width != 0))

+	return (XpmFileInvalid);

     if ((height > 0 && width >= UINT_MAX / height) ||

 	width * height >= UINT_MAX / sizeof(unsigned int))

@@ -428,7 +435,11 @@ ParsePixels(

 		colidx[(unsigned char)colorTable[a].string[0]] = a + 1;

 	    for (y = 0; y < height; y++) {

-		xpmNextString(data);

+		ErrorStatus = xpmNextString(data);

+		if (ErrorStatus != XpmSuccess) {

+		    XpmFree(iptr2);

+		    return (ErrorStatus);

+		}

 		for (x = 0; x < width; x++, iptr++) {

 		    int c = xpmGetC(data);

@@ -475,7 +486,11 @@ do \

 	    }

 	    for (y = 0; y < height; y++) {

-		xpmNextString(data);

+		ErrorStatus = xpmNextString(data);

+		if (ErrorStatus != XpmSuccess) {

+		    XpmFree(iptr2);

+		    return (ErrorStatus);

+		}

 		for (x = 0; x < width; x++, iptr++) {

 		    int cc1 = xpmGetC(data);

 		    if (cc1 > 0 && cc1 < 256) {

@@ -515,7 +530,11 @@ do \

 		xpmHashAtom *slot;

 		for (y = 0; y < height; y++) {

-		    xpmNextString(data);

+		    ErrorStatus = xpmNextString(data);

+		    if (ErrorStatus != XpmSuccess) {

+			XpmFree(iptr2);

+			return (ErrorStatus);

+		    }

 		    for (x = 0; x < width; x++, iptr++) {

 			for (a = 0, s = buf; a < cpp; a++, s++) {

 			    int c = xpmGetC(data);

@@ -535,7 +554,11 @@ do \

 		}

 	    } else {

 		for (y = 0; y < height; y++) {

-		    xpmNextString(data);

+		    ErrorStatus = xpmNextString(data);

+		    if (ErrorStatus != XpmSuccess) {

+			XpmFree(iptr2);

+			return (ErrorStatus);

+		    }

 		    for (x = 0; x < width; x++, iptr++) {

 			for (a = 0, s = buf; a < cpp; a++, s++) {

 			    int c = xpmGetC(data);

-- 

2.39.0