PyOS_getsig(), PyOS_setsig(): The minimal amount of work to avoid the
uninitialized memory reads reported in bug #478001.
Note that this doesn't address the following larger issues:
- Error conditions are not documented for PyOS_*sig() in the C API.
- Nothing that actually calls PyOS_*sig() in the core interpreter and
extension modules actually /checks/ the return value of the call.
Fixing those is left as an exercise for a later day.
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 963df8a..f6217c3 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1437,6 +1437,12 @@
{
#ifdef HAVE_SIGACTION
struct sigaction context;
+ /* Initialize context.sa_handler to SIG_ERR which makes about as
+ * much sense as anything else. It should get overwritten if
+ * sigaction actually succeeds and otherwise we avoid an
+ * uninitialized memory read.
+ */
+ context.sa_handler = SIG_ERR;
sigaction(sig, NULL, &context);
return context.sa_handler;
#else
@@ -1453,6 +1459,12 @@
#ifdef HAVE_SIGACTION
struct sigaction context;
PyOS_sighandler_t oldhandler;
+ /* Initialize context.sa_handler to SIG_ERR which makes about as
+ * much sense as anything else. It should get overwritten if
+ * sigaction actually succeeds and otherwise we avoid an
+ * uninitialized memory read.
+ */
+ context.sa_handler = SIG_ERR;
sigaction(sig, NULL, &context);
oldhandler = context.sa_handler;
context.sa_handler = handler;