From 9b21c88bc668236e63601509857664522267abe2 Mon Sep 17 00:00:00 2001
From: Alexander Boettcher <alexander.boettcher@genode-labs.com>
Date: Wed, 9 Sep 2015 23:28:36 +0200
Subject: [PATCH] base: handle unsupported printf commands better

The commit consumes the argument of a unsupported printf command.

Without the commit - a subsequent command uses the argument of the preceding
command, which may cause memory corruption or page faults for sequences using
string commands, e.g.

Genode::printf("%#x %s\n", 0x20, "Test");

'#' is not supported by Genode::printf. In this scenario a pagefault at
address 0x20 is caused.

Fixes #1701
---
 repos/base/src/base/console/console.cc | 2 ++
 repos/base/src/test/printf/main.cc     | 4 ++++
 tool/autopilot.list                    | 1 +
 3 files changed, 7 insertions(+)

diff --git a/repos/base/src/base/console/console.cc b/repos/base/src/base/console/console.cc
index d2724c739..cb615c2a3 100644
--- a/repos/base/src/base/console/console.cc
+++ b/repos/base/src/base/console/console.cc
@@ -335,6 +335,8 @@ void Console::vprintf(const char *format, va_list list)
 			case Format_command::INVALID:
 
 				_out_string("<warning: unsupported format string argument>");
+				/* consume the argument of the unsupported command */
+				va_arg(list, long);
 				break;
 		}
 
diff --git a/repos/base/src/test/printf/main.cc b/repos/base/src/test/printf/main.cc
index 77d911856..51b617d35 100644
--- a/repos/base/src/test/printf/main.cc
+++ b/repos/base/src/test/printf/main.cc
@@ -16,6 +16,10 @@
 
 int main(int argc, char **argv)
 {
+	/* test that unsupported commands don't crash the printf parser */
+	Genode::printf("%#x %s\n", 0x38, "test 1");
+	Genode::printf("%#lx %s\n", 0x38L, "test 2");
+
 	Genode::printf("-1 = %d = %ld\n", -1, -1L);
 
 	return 0;
diff --git a/tool/autopilot.list b/tool/autopilot.list
index f6c281064..5718fb8c9 100644
--- a/tool/autopilot.list
+++ b/tool/autopilot.list
@@ -55,3 +55,4 @@ stdcxx
 nic_loopback
 platform
 report_rom
+printf