linux-kernel - [PATCH] exit: Allow oops

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Message-Id: <20221202210617.never.105-kees@kernel.org>
Date:   Fri,  2 Dec 2022 13:06:21 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Jann Horn <jannh@...gle.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Seth Jenkins <sethjenkins@...gle.com>,
        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>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Arnd Bergmann <arnd@...db.de>, linux-doc@...r.kernel.org,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        Joel Savitz <jsavitz@...hat.com>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        Rob Herring <robh@...nel.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Ingo Molnar <mingo@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH] exit: Allow oops_limit to be disabled

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: Seth Jenkins <sethjenkins@...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>
---
I've changed the warn_limit logic to match...
---
 Documentation/admin-guide/sysctl/kernel.rst | 5 +++--
 kernel/exit.c                               | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 09f3fb2f8585..a31d8d81ea07 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -671,8 +671,9 @@ 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.
 
 
 osrelease, ostype & version
diff --git a/kernel/exit.c b/kernel/exit.c
index dc1a32149f94..deffb8e4b1b2 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -954,7 +954,7 @@ 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);
 
 	/*
-- 
2.34.1