From: He Zhe <[email protected]>
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 and changes some printk
to right fashion.
Signed-off-by: He Zhe <[email protected]>
---
drivers/tty/serial/kgdboc.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index b4ba2b1..0003d6c 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -130,8 +130,13 @@ 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");
+ pr_err("kgdboc: config string too long\n");
return -ENOSPC;
}
strcpy(config, opt);
@@ -248,7 +253,7 @@ static int param_set_kgdboc_var(const char *kmessage,
int len = strlen(kmessage);
if (len >= MAX_CONFIG_LEN) {
- printk(KERN_ERR "kgdboc: config string too long\n");
+ pr_err("kgdboc: config string too long\n");
return -ENOSPC;
}
@@ -259,8 +264,7 @@ static int param_set_kgdboc_var(const char *kmessage,
}
if (kgdb_connected) {
- printk(KERN_ERR
- "kgdboc: Cannot reconfigure while KGDB is connected.\n");
+ pr_err("kgdboc: Cannot reconfigure while KGDB is connected.\n");
return -EBUSY;
}
--
2.7.4
On Wed, Aug 08, 2018 at 11:59:44PM +0800, [email protected] wrote:
> From: He Zhe <[email protected]>
>
> 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 and changes some printk
> to right fashion.
>
> Signed-off-by: He Zhe <[email protected]>
For the bug fix portions of this patch you should add the stable kernel
ML to the Cc: of the sign off area: See:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1
> ---
> drivers/tty/serial/kgdboc.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
> index b4ba2b1..0003d6c 100644
> --- a/drivers/tty/serial/kgdboc.c
> +++ b/drivers/tty/serial/kgdboc.c
> @@ -130,8 +130,13 @@ 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");
> + pr_err("kgdboc: config string too long\n");
These changes are not bug fixes and are not normally candidates for
backporting. It would therefore be better to put the s/printk KERN_ERR /pr_err(/
changes into a separate patch.
> return -ENOSPC;
> }
> strcpy(config, opt);
> @@ -248,7 +253,7 @@ static int param_set_kgdboc_var(const char *kmessage,
> int len = strlen(kmessage);
>
> if (len >= MAX_CONFIG_LEN) {
> - printk(KERN_ERR "kgdboc: config string too long\n");
> + pr_err("kgdboc: config string too long\n");
> return -ENOSPC;
> }
>
> @@ -259,8 +264,7 @@ static int param_set_kgdboc_var(const char *kmessage,
> }
>
> if (kgdb_connected) {
> - printk(KERN_ERR
> - "kgdboc: Cannot reconfigure while KGDB is connected.\n");
> + pr_err("kgdboc: Cannot reconfigure while KGDB is connected.\n");
>
> return -EBUSY;
> }
> --
> 2.7.4
>