openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 141 insertions, 0 deletions

diff --git a/tools/perf/ui/setup.c b/tools/perf/ui/setup.c
new file mode 100644
index 000000000..ff800047e
--- /dev/null
+++ b/tools/perf/ui/setup.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <dlfcn.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include <subcmd/pager.h>
+#include "../util/debug.h"
+#include "../util/hist.h"
+#include "ui.h"
+
+struct mutex ui__lock;
+void *perf_gtk_handle;
+int use_browser = -1;
+
+#define PERF_GTK_DSO "libperf-gtk.so"
+
+#ifdef HAVE_GTK2_SUPPORT
+
+static int setup_gtk_browser(void)
+{
+	int (*perf_ui_init)(void);
+
+	if (perf_gtk_handle)
+		return 0;
+
+	perf_gtk_handle = dlopen(PERF_GTK_DSO, RTLD_LAZY);
+	if (perf_gtk_handle == NULL) {
+		char buf[PATH_MAX];
+		scnprintf(buf, sizeof(buf), "%s/%s", LIBDIR, PERF_GTK_DSO);
+		perf_gtk_handle = dlopen(buf, RTLD_LAZY);
+	}
+	if (perf_gtk_handle == NULL)
+		return -1;
+
+	perf_ui_init = dlsym(perf_gtk_handle, "perf_gtk__init");
+	if (perf_ui_init == NULL)
+		goto out_close;
+
+	if (perf_ui_init() == 0)
+		return 0;
+
+out_close:
+	dlclose(perf_gtk_handle);
+	return -1;
+}
+
+static void exit_gtk_browser(bool wait_for_ok)
+{
+	void (*perf_ui_exit)(bool);
+
+	if (perf_gtk_handle == NULL)
+		return;
+
+	perf_ui_exit = dlsym(perf_gtk_handle, "perf_gtk__exit");
+	if (perf_ui_exit == NULL)
+		goto out_close;
+
+	perf_ui_exit(wait_for_ok);
+
+out_close:
+	dlclose(perf_gtk_handle);
+
+	perf_gtk_handle = NULL;
+}
+#else
+static inline int setup_gtk_browser(void) { return -1; }
+static inline void exit_gtk_browser(bool wait_for_ok __maybe_unused) {}
+#endif
+
+int stdio__config_color(const struct option *opt __maybe_unused,
+			const char *mode, int unset __maybe_unused)
+{
+	perf_use_color_default = perf_config_colorbool("color.ui", mode, -1);
+	return 0;
+}
+
+void setup_browser(bool fallback_to_pager)
+{
+	mutex_init(&ui__lock);
+	if (use_browser < 2 && (!isatty(1) || dump_trace))
+		use_browser = 0;
+
+	/* default to TUI */
+	if (use_browser < 0)
+		use_browser = 1;
+
+	switch (use_browser) {
+	case 2:
+		if (setup_gtk_browser() == 0)
+			break;
+		printf("GTK browser requested but could not find %s\n",
+		       PERF_GTK_DSO);
+		sleep(1);
+		use_browser = 1;
+		/* fall through */
+	case 1:
+		if (ui__init() == 0)
+			break;
+		/* fall through */
+	default:
+		use_browser = 0;
+		if (fallback_to_pager)
+			setup_pager();
+		break;
+	}
+}
+
+void exit_browser(bool wait_for_ok)
+{
+	switch (use_browser) {
+	case 2:
+		exit_gtk_browser(wait_for_ok);
+		break;
+
+	case 1:
+		ui__exit(wait_for_ok);
+		break;
+
+	default:
+		break;
+	}
+	mutex_destroy(&ui__lock);
+}
+
+void pthread__block_sigwinch(void)
+{
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, SIGWINCH);
+	pthread_sigmask(SIG_BLOCK, &set, NULL);
+}
+
+void pthread__unblock_sigwinch(void)
+{
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, SIGWINCH);
+	pthread_sigmask(SIG_UNBLOCK, &set, NULL);
+}