[PATCH] [cairo-matrix] Check for non-finite numbers in the matrices.

[Chris Wilson]

Add a C99 isfinite() check on the matrix determinant which should catch
all attempts to corrupt our matrices.
---
 configure.in       |    8 ++++++++
 src/cairo-matrix.c |    9 +++++++++
 2 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/configure.in b/configure.in
index e8a6191..0859b94 100644
--- a/configure.in
+++ b/configure.in
@@ -701,6 +701,9 @@ AC_MSG_RESULT([$warn_unused_result])
 CAIRO_CC_TRY_FLAG([-fno-strict-aliasing],
 		  [CAIRO_CFLAGS="$CAIRO_CFLAGS -fno-strict-aliasing"
 		   PIXMAN_CFLAGS="$PIXMAN_CFLAGS -fno-strict-aliasing"])
+CAIRO_CC_TRY_FLAG([-std=gnu99],
+		  [CFLAGS="-std=gnu99 $CFLAGS"
+		   CAIRO_CFLAGS="-std=gnu99 $CAIRO_CFLAGS"])
 
 AC_SUBST(CAIRO_REQUIRES)
 AC_SUBST(CAIRO_NONPKGCONFIG_CFLAGS)
@@ -712,6 +715,11 @@ AC_SUBST(PIXMAN_CFLAGS)
 AC_SUBST(PIXMAN_LDADD)
 AC_SUBST(CAIROPERF_LIBS)
 
+# isfinite() depends on a C99 compiler
+AC_TRY_LINK([#include <math.h>],
+	    [isfinite(1.0)],
+  AC_DEFINE(HAVE_ISFINITE, 1, [Define to 1 if you have isfinite() ]))
+
 dnl ===========================================================================
 dnl Check for gtk-doc and docbook
 
diff --git a/src/cairo-matrix.c b/src/cairo-matrix.c
index a504ea6..8e0daa2 100644
--- a/src/cairo-matrix.c
+++ b/src/cairo-matrix.c
@@ -474,6 +474,10 @@ cairo_matrix_invert (cairo_matrix_t *matrix)
 
     if (det == 0)
 	return CAIRO_STATUS_INVALID_MATRIX;
+#ifdef HAVE_ISFINITE
+    if (! isfinite (det))
+	return CAIRO_STATUS_INVALID_MATRIX;
+#endif
 
     _cairo_matrix_compute_adjoint (matrix);
     _cairo_matrix_scalar_multiply (matrix, 1 / det);

--9jxsPFA5p3P2qPhR--