From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: [PATCH v2 1/2] kgdboc: Passing ekgdboc to command line causes panic Date: Tue, 14 Aug 2018 20:46:00 +0800 Message-ID: <1534250761-824-1-git-send-email-zhe.he@windriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kgdb-bugreport-bounces@lists.sourceforge.net To: jason.wessel@windriver.com, daniel.thompson@linaro.org, gregkh@linuxfoundation.org, jslaby@suse.com, kgdb-bugreport@lists.sourceforge.net, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Cc: zhe.he@windriver.com List-Id: linux-serial@vger.kernel.org From: He Zhe kgdboc_option_setup does not check input argument before passing it to strlen. The argument would be a NULL pointer if "ekgdboc", without its value, is set in command line and thus cause the following panic. PANIC: early exception 0xe3 IP 10:ffffffff8fbbb620 error 0 cr2 0x0 [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.18-rc8+ #1 [ 0.000000] RIP: 0010:strlen+0x0/0x20 ... [ 0.000000] Call Trace [ 0.000000] ? kgdboc_option_setup+0x9/0xa0 [ 0.000000] ? kgdboc_early_init+0x6/0x1b [ 0.000000] ? do_early_param+0x4d/0x82 [ 0.000000] ? parse_args+0x212/0x330 [ 0.000000] ? rdinit_setup+0x26/0x26 [ 0.000000] ? parse_early_options+0x20/0x23 [ 0.000000] ? rdinit_setup+0x26/0x26 [ 0.000000] ? parse_early_param+0x2d/0x39 [ 0.000000] ? setup_arch+0x2f7/0xbf4 [ 0.000000] ? start_kernel+0x5e/0x4c2 [ 0.000000] ? load_ucode_bsp+0x113/0x12f [ 0.000000] ? secondary_startup_64+0xa5/0xb0 This patch adds a check to prevent the panic. Cc: stable@vger.kernel.org Signed-off-by: He Zhe --- v2: - Split out printk cleanups - Add cc to stable@vger.kernel.org drivers/tty/serial/kgdboc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c index b4ba2b1..206f8c2 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -130,6 +130,11 @@ static void kgdboc_unregister_kbd(void) static int kgdboc_option_setup(char *opt) { + if (!opt) { + pr_err("kgdboc: null option\n"); + return -EINVAL; + } + if (strlen(opt) >= MAX_CONFIG_LEN) { printk(KERN_ERR "kgdboc: config string too long\n"); return -ENOSPC; -- 2.7.4 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot