From:   Eric Biggers <ebiggers@kernel.org>
To:     stable@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Kees Cook <keescook@chromium.org>, SeongJae Park <sj@kernel.org>,
        Seth Jenkins <sethjenkins@google.com>,
        Jann Horn <jannh@google.com>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jonathan Corbet <corbet@lwn.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Baolin Wang <baolin.wang@linux.alibaba.com>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Eric Biggers <ebiggers@google.com>,
        Huang Ying <ying.huang@intel.com>,
        Arnd Bergmann <arnd@arndb.de>, linux-doc@vger.kernel.org
Subject: [PATCH 5.15 15/20] exit: Allow oops_limit to be disabled
Date:   Tue, 24 Jan 2023 10:51:05 -0800
Message-Id: <20230124185110.143857-16-ebiggers@kernel.org>
In-Reply-To: <20230124185110.143857-1-ebiggers@kernel.org>
References: <20230124185110.143857-1-ebiggers@kernel.org>
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From: Kees Cook <keescook@chromium.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@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 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 b6e68d6f297e5..d6f1d3892e71e 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -675,8 +675,9 @@ 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 f68a9c6adfc9c..f6c85101dba0f 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -941,7 +941,7 @@ 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