From d98e5a2ace46adcefa093c029663575fd677bf05 Mon Sep 17 00:00:00 2001
From: Ondrej Dubaj <odubaj@redhat.com>
Date: Tue, 4 Jun 2019 13:05:57 +0200
Subject: [PATCH] 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 | 19 +++++++++++++++----
src/gd_jpeg.c | 20 ++++++++++++++++----
src/gd_wbmp.c | 21 ++++++++++++++++++---
tests/jpeg/CMakeLists.txt | 1 +
tests/jpeg/Makemodule.am | 3 ++-
tests/jpeg/jpeg_ptr_double_free.c | 31 +++++++++++++++++++++++++++++++
6 files changed, 83 insertions(+), 12 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 6fe707d..4a05c09 100755
--- a/src/gd_gif_out.c
+++ b/src/gd_gif_out.c
@@ -99,7 +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 +131,11 @@ 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 +223,12 @@ 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 +240,7 @@ 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 +256,8 @@ 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 271ef46..bd8fc27 100755
--- 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 +422,7 @@ 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 0028273..341ff6e 100755
--- 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;
}
diff --git a/tests/jpeg/CMakeLists.txt b/tests/jpeg/CMakeLists.txt
index 19964b0..a8d8162 100755
--- a/tests/jpeg/CMakeLists.txt
+++ b/tests/jpeg/CMakeLists.txt
@@ -2,6 +2,7 @@ IF(JPEG_FOUND)
LIST(APPEND TESTS_FILES
jpeg_empty_file
jpeg_im2im
+ jpeg_ptr_double_free
jpeg_null
)
diff --git a/tests/jpeg/Makemodule.am b/tests/jpeg/Makemodule.am
index 7e5d317..b89e169 100755
--- a/tests/jpeg/Makemodule.am
+++ b/tests/jpeg/Makemodule.am
@@ -2,7 +2,8 @@ if HAVE_LIBJPEG
libgd_test_programs += \
jpeg/jpeg_empty_file \
jpeg/jpeg_im2im \
- jpeg/jpeg_null
+ jpeg/jpeg_null \
+ jpeg/jpeg_ptr_double_free
if HAVE_LIBPNG
libgd_test_programs += \
diff --git a/tests/jpeg/jpeg_ptr_double_free.c b/tests/jpeg/jpeg_ptr_double_free.c
new file mode 100644
index 0000000..c80aeb6
--- /dev/null
+++ b/tests/jpeg/jpeg_ptr_double_free.c
@@ -0,0 +1,31 @@
+/**
+ * Test that failure to convert to JPEG returns NULL
+ *
+ * We are creating an image, set its width to zero, and pass this image to
+ * `gdImageJpegPtr()` which is supposed to fail, and as such should return NULL.
+ *
+ * See also <https://github.com/libgd/libgd/issues/381>
+ */
+
+
+#include "gd.h"
+#include "gdtest.h"
+
+
+int main()
+{
+ gdImagePtr src, dst;
+ int size;
+
+ src = gdImageCreateTrueColor(1, 10);
+ gdTestAssert(src != NULL);
+
+ src->sx = 0; /* this hack forces gdImageJpegPtr() to fail */
+
+ dst = gdImageJpegPtr(src, &size, 0);
+ gdTestAssert(dst == NULL);
+
+ gdImageDestroy(src);
+
+ return gdNumFailures();
+}
\ No newline at end of file
--
2.17.1