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From 553702980ae89c83f2d6e254d62cf82e204956d0 Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Thu, 17 Jan 2019 11:54:55 +0100
Subject: [PATCH] Fix #492: Potential double-free in gdImage*Ptr()
Whenever `gdImage*Ptr()` calls `gdImage*Ctx()` and the latter fails, we
must not call `gdDPExtractData()`; otherwise a double-free would
happen. Since `gdImage*Ctx()` are void functions, and we can't change
that for BC reasons, we're introducing static helpers which are used
internally.
We're adding a regression test for `gdImageJpegPtr()`, but not for
`gdImageGifPtr()` and `gdImageWbmpPtr()` since we don't know how to
trigger failure of the respective `gdImage*Ctx()` calls.
This potential security issue has been reported by Solmaz Salimi (aka.
Rooney).
---
src/gd_gif_out.c | 18 +++++++++++++++---
src/gd_jpeg.c | 20 ++++++++++++++++----
src/gd_wbmp.c | 21 ++++++++++++++++++---
tests/jpeg/.gitignore | 1 +
tests/jpeg/CMakeLists.txt | 1 +
tests/jpeg/Makemodule.am | 3 ++-
tests/jpeg/jpeg_ptr_double_free.c | 31 +++++++++++++++++++++++++++++++
7 files changed, 84 insertions(+), 11 deletions(-)
create mode 100644 tests/jpeg/jpeg_ptr_double_free.c
diff --git a/src/gd_gif_out.c b/src/gd_gif_out.c
index 298a5812..d5a95346 100644
--- a/src/gd_gif_out.c
+++ b/src/gd_gif_out.c
@@ -99,6 +99,7 @@ static void char_init(GifCtx *ctx);
static void char_out(int c, GifCtx *ctx);
static void flush_char(GifCtx *ctx);
+static int _gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out);
@@ -131,8 +132,11 @@ BGD_DECLARE(void *) gdImageGifPtr(gdImagePtr im, int *size)
void *rv;
gdIOCtx *out = gdNewDynamicCtx(2048, NULL);
if (out == NULL) return NULL;
- gdImageGifCtx(im, out);
- rv = gdDPExtractData(out, size);
+ if (!_gdImageGifCtx(im, out)) {
+ rv = gdDPExtractData(out, size);
+ } else {
+ rv = NULL;
+ }
out->gd_free(out);
return rv;
}
@@ -220,6 +224,12 @@ BGD_DECLARE(void) gdImageGif(gdImagePtr im, FILE *outFile)
*/
BGD_DECLARE(void) gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
+{
+ _gdImageGifCtx(im, out);
+}
+
+/* returns 0 on success, 1 on failure */
+static int _gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
{
gdImagePtr pim = 0, tim = im;
int interlace, BitsPerPixel;
@@ -231,7 +241,7 @@ BGD_DECLARE(void) gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
based temporary image. */
pim = gdImageCreatePaletteFromTrueColor(im, 1, 256);
if(!pim) {
- return;
+ return 1;
}
tim = pim;
}
@@ -247,6 +257,8 @@ BGD_DECLARE(void) gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
/* Destroy palette based temporary image. */
gdImageDestroy( pim);
}
+
+ return 0;
}
diff --git a/src/gd_jpeg.c b/src/gd_jpeg.c
index fc058420..96ef4302 100644
--- a/src/gd_jpeg.c
+++ b/src/gd_jpeg.c
@@ -123,6 +123,8 @@ static void fatal_jpeg_error(j_common_ptr cinfo)
exit(99);
}
+static int _gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality);
+
/*
* Write IM to OUTFILE as a JFIF-formatted JPEG image, using quality
* QUALITY. If QUALITY is in the range 0-100, increasing values
@@ -237,8 +239,11 @@ BGD_DECLARE(void *) gdImageJpegPtr(gdImagePtr im, int *size, int quality)
void *rv;
gdIOCtx *out = gdNewDynamicCtx(2048, NULL);
if (out == NULL) return NULL;
- gdImageJpegCtx(im, out, quality);
- rv = gdDPExtractData(out, size);
+ if (!_gdImageJpegCtx(im, out, quality)) {
+ rv = gdDPExtractData(out, size);
+ } else {
+ rv = NULL;
+ }
out->gd_free(out);
return rv;
}
@@ -259,6 +264,12 @@ void jpeg_gdIOCtx_dest(j_compress_ptr cinfo, gdIOCtx *outfile);
*/
BGD_DECLARE(void) gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
+{
+ _gdImageJpegCtx(im, outfile, quality);
+}
+
+/* returns 0 on success, 1 on failure */
+static int _gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
{
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
@@ -293,7 +304,7 @@ BGD_DECLARE(void) gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
if(row) {
gdFree(row);
}
- return;
+ return 1;
}
cinfo.err->emit_message = jpeg_emit_message;
@@ -334,7 +345,7 @@ BGD_DECLARE(void) gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
if(row == 0) {
gd_error("gd-jpeg: error: unable to allocate JPEG row structure: gdCalloc returns NULL\n");
jpeg_destroy_compress(&cinfo);
- return;
+ return 1;
}
rowptr[0] = row;
@@ -411,6 +424,7 @@ BGD_DECLARE(void) gdImageJpegCtx(gdImagePtr im, gdIOCtx *outfile, int quality)
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
gdFree(row);
+ return 0;
}
diff --git a/src/gd_wbmp.c b/src/gd_wbmp.c
index f19a1c96..a49bdbec 100644
--- a/src/gd_wbmp.c
+++ b/src/gd_wbmp.c
@@ -88,6 +88,8 @@ int gd_getin(void *in)
return (gdGetC((gdIOCtx *)in));
}
+static int _gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out);
+
/*
Function: gdImageWBMPCtx
@@ -100,6 +102,12 @@ int gd_getin(void *in)
out - the stream where to write
*/
BGD_DECLARE(void) gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out)
+{
+ _gdImageWBMPCtx(image, fg, out);
+}
+
+/* returns 0 on success, 1 on failure */
+static int _gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out)
{
int x, y, pos;
Wbmp *wbmp;
@@ -107,7 +115,7 @@ BGD_DECLARE(void) gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out)
/* create the WBMP */
if((wbmp = createwbmp(gdImageSX(image), gdImageSY(image), WBMP_WHITE)) == NULL) {
gd_error("Could not create WBMP\n");
- return;
+ return 1;
}
/* fill up the WBMP structure */
@@ -123,11 +131,15 @@ BGD_DECLARE(void) gdImageWBMPCtx(gdImagePtr image, int fg, gdIOCtx *out)
/* write the WBMP to a gd file descriptor */
if(writewbmp(wbmp, &gd_putout, out)) {
+ freewbmp(wbmp);
gd_error("Could not save WBMP\n");
+ return 1;
}
/* des submitted this bugfix: gdFree the memory. */
freewbmp(wbmp);
+
+ return 0;
}
/*
@@ -271,8 +283,11 @@ BGD_DECLARE(void *) gdImageWBMPPtr(gdImagePtr im, int *size, int fg)
void *rv;
gdIOCtx *out = gdNewDynamicCtx(2048, NULL);
if (out == NULL) return NULL;
- gdImageWBMPCtx(im, fg, out);
- rv = gdDPExtractData(out, size);
+ if (!_gdImageWBMPCtx(im, fg, out)) {
+ rv = gdDPExtractData(out, size);
+ } else {
+ rv = NULL;
+ }
out->gd_free(out);
return rv;
}
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