Re: [PATCH v2 1/2] kgdboc: Passing ekgdboc to command line causes panic
From: Daniel Thompson <hidden>
Date: 2018-08-14 13:27:06
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On Tue, Aug 14, 2018 at 08:46:00PM +0800, zhe.he@windriver.com wrote:
quoted hunk ↗ jump to hunk
From: He Zhe <redacted> 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 <redacted> --- 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");
Apologies... I should have picked this up when I replied earlier but
this error message describes what the function gets when I think it
should report what the user actually did. So should be something like:
pr_err("kgdboc: config string not provided\n");
With that (or a very similar) change:
Reviewed-by: Daniel Thompson <redacted>
Daniel.
+ return -EINVAL;
+ }
+
if (strlen(opt) >= MAX_CONFIG_LEN) {
printk(KERN_ERR "kgdboc: config string too long\n");
return -ENOSPC;
--
2.7.4