linux-hardening - [PATCH 4.14 v2 10/15] exit: Allow oops

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Message-Id: <20230203003354.85691-11-ebiggers@kernel.org>
Date:   Thu,  2 Feb 2023 16:33:49 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     stable@...r.kernel.org
Cc:     Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>,
        Kees Cook <keescook@...omium.org>,
        SeongJae Park <sj@...nel.org>,
        Seth Jenkins <sethjenkins@...gle.com>,
        Jann Horn <jannh@...gle.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Eric Biggers <ebiggers@...gle.com>,
        Huang Ying <ying.huang@...el.com>,
        Arnd Bergmann <arnd@...db.de>, linux-doc@...r.kernel.org
Subject: [PATCH 4.14 v2 10/15] exit: Allow oops_limit to be disabled

From: Kees Cook <keescook@...omium.org>

commit de92f65719cd672f4b48397540b9f9eff67eca40 upstream.

In preparation for keeping oops_limit logic in sync with warn_limit,
have oops_limit == 0 disable checking the Oops counter.

Cc: Jann Horn <jannh@...gle.com>
Cc: Jonathan Corbet <corbet@....net>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Eric Biggers <ebiggers@...gle.com>
Cc: Huang Ying <ying.huang@...el.com>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: linux-doc@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 Documentation/sysctl/kernel.txt | 5 +++--
 kernel/exit.c                   | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 7b04c616c5901..b6124a4475fb7 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -519,8 +519,9 @@ scanned for a given scan.
 oops_limit:
 
 Number of kernel oopses after which the kernel should panic when
-``panic_on_oops`` is not set. Setting this to 0 or 1 has the same effect
-as setting ``panic_on_oops=1``.
+``panic_on_oops`` is not set. Setting this to 0 disables checking
+the count. Setting this to  1 has the same effect as setting
+``panic_on_oops=1``. The default value is 10000.
 
 ==============================================================
 
diff --git a/kernel/exit.c b/kernel/exit.c
index 138b110bf83a1..73103e008a627 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -984,7 +984,7 @@ void __noreturn make_task_dead(int signr)
 	 * To make sure this can't happen, place an upper bound on how often the
 	 * kernel may oops without panic().
 	 */
-	if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit))
+	if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit) && oops_limit)
 		panic("Oopsed too often (kernel.oops_limit is %d)", oops_limit);
 
 	do_exit(signr);
-- 
2.39.1