4.4-stable review patch. If anyone has any objections, please let me know.
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From: He Zhe zhe.he@windriver.com
commit 1bd54d851f50dea6af30c3e6ff4f3e9aab5558f9 upstream.
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 Cc: jason.wessel@windriver.com Cc: gregkh@linuxfoundation.org Cc: jslaby@suse.com Signed-off-by: He Zhe zhe.he@windriver.com Reviewed-by: Daniel Thompson daniel.thompson@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tty/serial/kgdboc.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -133,6 +133,11 @@ static void kgdboc_unregister_kbd(void)
static int kgdboc_option_setup(char *opt) { + if (!opt) { + pr_err("kgdboc: config string not provided\n"); + return -EINVAL; + } + if (strlen(opt) >= MAX_CONFIG_LEN) { printk(KERN_ERR "kgdboc: config string too long\n"); return -ENOSPC;