Merge branch 'gtksecurememory-updates' into 'master'

gtksecurememory: Request that secure memory not be dumped to disk

See merge request GNOME/gtk!3452

3 files changed, 20 insertions, 1 deletions

diff --git a/config.h.meson b/config.h.meson
index fc2dd0b3d2..bc1d778f2c 100644
--- a/config.h.meson
+++ b/config.h.meson
@@ -76,6 +76,9 @@
 /* Define to 1 if you have a working `mmap' system call. */
 #mesondefine HAVE_MMAP
 
+/* Define to 1 if you have a working `madvise' system call. */
+#mesondefine HAVE_MADVISE
+
 /* Define to 1 if you have the `posix_fallocate' function. */
 #mesondefine HAVE_POSIX_FALLOCATE
 
diff --git a/gtk/gtksecurememory.c b/gtk/gtksecurememory.c
index 35a6f6b875..a7aa34c447 100644
--- a/gtk/gtksecurememory.c
+++ b/gtk/gtksecurememory.c
@@ -943,6 +943,19 @@ sec_acquire_pages (size_t *sz,
 
 	DEBUG_ALLOC ("gtk-secure-memory: new block ", *sz);
 
+#if defined(HAVE_MADVISE) && defined(MADV_DONTDUMP)
+	if (madvise (pages, *sz, MADV_DONTDUMP) < 0) {
+		if (show_warning && gtk_secure_warnings) {
+			/*
+			 * Not fatal - this was added in Linux 3.4 and older
+			 * kernels will legitimately fail this at runtime
+			 */
+			fprintf (stderr, "couldn't MADV_DONTDUMP %lu bytes of memory (%s): %s\n",
+				 (unsigned long)*sz, during_tag, strerror (errno));
+		}
+	}
+#endif
+
 	show_warning = 1;
 	return pages;
 
diff --git a/meson.build b/meson.build
index eb012b549e..35803e6161 100644
--- a/meson.build
+++ b/meson.build
@@ -220,10 +220,13 @@ if cc.compiles(uint128_t_src, name : '__uint128_t available')
   cdata.set('HAVE_UINT128_T', 1)
 endif
 
-# Check for mlock
+# Check for mlock and madvise
 if cc.has_function('mlock', prefix: '#include <sys/mman.h>')
   cdata.set('HAVE_MLOCK', 1)
 endif
+if cc.has_function('madvise', prefix: '#include <sys/mman.h>')
+  cdata.set('HAVE_MADVISE', 1)
+endif
 
 # Disable deprecation checks for all libraries we depend on on stable branches.
 # This is so newer versions of those libraries don't cause more warnings with