From 9db89b41117024f80b38b15954017fb293133364 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Thu, 17 Nov 2022 15:43:23 -0800
Subject: exit: Expose "oops_count" to sysfs

Since Oops count is now tracked and is a fairly interesting signal, add
the entry /sys/kernel/oops_count to expose it to userspace.

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jann Horn <jannh@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221117234328.594699-3-keescook@chromium.org
---
 kernel/exit.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

(limited to 'kernel/exit.c')

diff --git a/kernel/exit.c b/kernel/exit.c
index 2ab3ead62118..dc1a32149f94 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -67,6 +67,7 @@
 #include <linux/io_uring.h>
 #include <linux/kprobes.h>
 #include <linux/rethook.h>
+#include <linux/sysfs.h>
 
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
@@ -99,6 +100,25 @@ static __init int kernel_exit_sysctls_init(void)
 late_initcall(kernel_exit_sysctls_init);
 #endif
 
+static atomic_t oops_count = ATOMIC_INIT(0);
+
+#ifdef CONFIG_SYSFS
+static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr,
+			       char *page)
+{
+	return sysfs_emit(page, "%d\n", atomic_read(&oops_count));
+}
+
+static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count);
+
+static __init int kernel_exit_sysfs_init(void)
+{
+	sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL);
+	return 0;
+}
+late_initcall(kernel_exit_sysfs_init);
+#endif
+
 static void __unhash_process(struct task_struct *p, bool group_dead)
 {
 	nr_threads--;
@@ -901,8 +921,6 @@ void __noreturn do_exit(long code)
 
 void __noreturn make_task_dead(int signr)
 {
-	static atomic_t oops_count = ATOMIC_INIT(0);
-
 	/*
 	 * Take the task off the cpu after something catastrophic has
 	 * happened.
-- 
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