From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C941B1DB127; Tue, 8 Jul 2025 16:55:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751993721; cv=none; b=YK9ZPLy3K48UTLyQ0eCQ2dA3GNA2JmiG02JkLpuPcOqKnBcKB8b/FM+kyG9HpCxMH4Dsy1rpP+uhmui4nu4/g9t+IweDV1ZvAfaO0zenwoRWdyuqAhcr6aRVlT8/WmgrZ6Z9+49Yv9+Eqat0hKkZyTfXQBJ8sIBPKytC3Tn58gA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751993721; c=relaxed/simple; bh=vR/tOs+4iwYGMY0rnVGHF5AdcX+L3rfJ7aNtKE6fr4Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tRizwmqfK9xh5Onys/XSO1+PLLnO8ynxZp9ipCjpRdEkT5dg/YyPGhQaB+QvcEkJbzbjj1moUWbRdopE7S596pyxJpnrBS7k1Wz+cSAgKrbBvFWLh/0z0zmL1+nQqCbTetsZD4YidsIPfiAy4WMTjsJQgobTHcsbIQbO58y68y4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AFlbMm+W; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="AFlbMm+W" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 552F0C4CEED; Tue, 8 Jul 2025 16:55:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1751993721; bh=vR/tOs+4iwYGMY0rnVGHF5AdcX+L3rfJ7aNtKE6fr4Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AFlbMm+Wz/n+KWsyXdiMAiN4Bh29v9dv+7XE2HmNUENXX3976SlCYH1qoPwojxt4g erda3uUPm5bBgmQ0eTDwgxITkM6Vu5XAvWEUfbDq+BiS/S/R7sqMHU1EpIiCuljuiv NNT0RdDmaU+AuRHrE+9nLULrx4fRt6hL3krbzsak= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Uladzislau Rezki (Sony)" , Joel Fernandes , Sasha Levin Subject: [PATCH 6.15 140/178] rcu: Return early if callback is not specified Date: Tue, 8 Jul 2025 18:22:57 +0200 Message-ID: <20250708162240.201669001@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250708162236.549307806@linuxfoundation.org> References: <20250708162236.549307806@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Uladzislau Rezki (Sony) [ Upstream commit 33b6a1f155d627f5bd80c7485c598ce45428f74f ] Currently the call_rcu() API does not check whether a callback pointer is NULL. If NULL is passed, rcu_core() will try to invoke it, resulting in NULL pointer dereference and a kernel crash. To prevent this and improve debuggability, this patch adds a check for NULL and emits a kernel stack trace to help identify a faulty caller. Signed-off-by: Uladzislau Rezki (Sony) Reviewed-by: Joel Fernandes Signed-off-by: Joel Fernandes Signed-off-by: Sasha Levin --- kernel/rcu/tree.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 80b10893b5038..37778d913f011 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3068,6 +3068,10 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in) /* Misaligned rcu_head! */ WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1)); + /* Avoid NULL dereference if callback is NULL. */ + if (WARN_ON_ONCE(!func)) + return; + if (debug_rcu_head_queue(head)) { /* * Probable double call_rcu(), so leak the callback. -- 2.39.5