[PATCH] driver: of: Properly truncate command line if too long

[PATCH] driver: of: Properly truncate command line if too long

[Alexandre Ghiti]

In case the command line given by the user is too long, warn about it
and truncate it to the last full argument.

This is what efi already does in commit 80b1bfe1cb2f ("efi/libstub:
Don't parse overlong command lines").

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 drivers/of/fdt.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index dcc1dd96911a..de4c6f9bac39 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -25,6 +25,7 @@
 #include <linux/serial_core.h>
 #include <linux/sysfs.h>
 #include <linux/random.h>
+#include <linux/ctype.h>
 
 #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
 #include <asm/page.h>
@@ -1050,9 +1051,27 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 
 	/* Retrieve command line */
 	p = of_get_flat_dt_prop(node, "bootargs", &l);
-	if (p != NULL && l > 0)
+	if (p != NULL && l > 0) {
 		strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
 
+		/*
+		 * If the given command line size is larger than
+		 * COMMAND_LINE_SIZE, truncate it to the last complete
+		 * parameter.
+		 */
+		if (l > COMMAND_LINE_SIZE) {
+			char *cmd_p = (char *)data + COMMAND_LINE_SIZE - 1;
+
+			while (!isspace(*cmd_p))
+				cmd_p--;
+
+			*cmd_p = '\0';
+
+			pr_err("Command line is too long: truncated to %d bytes\n",
+			       (int)(cmd_p - (char *)data + 1));
+		}
+	}
+
 	/*
 	 * CONFIG_CMDLINE is meant to be a default in case nothing else
 	 * managed to set the command line, unless CONFIG_CMDLINE_FORCE
-- 
2.20.1

Re: [PATCH] driver: of: Properly truncate command line if too long

[Alex Ghiti]

Hi,

Le 3/16/21 à 3:38 PM, Alexandre Ghiti a écrit :
> In case the command line given by the user is too long, warn about it
> and truncate it to the last full argument.
> 
> This is what efi already does in commit 80b1bfe1cb2f ("efi/libstub:
> Don't parse overlong command lines").
> 
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> ---
>   drivers/of/fdt.c | 21 ++++++++++++++++++++-
>   1 file changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index dcc1dd96911a..de4c6f9bac39 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -25,6 +25,7 @@
>   #include <linux/serial_core.h>
>   #include <linux/sysfs.h>
>   #include <linux/random.h>
> +#include <linux/ctype.h>
>   
>   #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
>   #include <asm/page.h>
> @@ -1050,9 +1051,27 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>   
>   	/* Retrieve command line */
>   	p = of_get_flat_dt_prop(node, "bootargs", &l);
> -	if (p != NULL && l > 0)
> +	if (p != NULL && l > 0) {
>   		strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
>   
> +		/*
> +		 * If the given command line size is larger than
> +		 * COMMAND_LINE_SIZE, truncate it to the last complete
> +		 * parameter.
> +		 */
> +		if (l > COMMAND_LINE_SIZE) {
> +			char *cmd_p = (char *)data + COMMAND_LINE_SIZE - 1;
> +
> +			while (!isspace(*cmd_p))
> +				cmd_p--;
> +
> +			*cmd_p = '\0';
> +
> +			pr_err("Command line is too long: truncated to %d bytes\n",
> +			       (int)(cmd_p - (char *)data + 1));
> +		}
> +	}
> +
>   	/*
>   	 * CONFIG_CMDLINE is meant to be a default in case nothing else
>   	 * managed to set the command line, unless CONFIG_CMDLINE_FORCE
> 

Any thought about that ?

Thanks,

Alex

Re: [PATCH] driver: of: Properly truncate command line if too long

[Rob Herring]

On Sat, Apr 3, 2021 at 7:09 AM Alex Ghiti <alex@ghiti.fr> wrote:
>
> Hi,
>
> Le 3/16/21 à 3:38 PM, Alexandre Ghiti a écrit :
> > In case the command line given by the user is too long, warn about it
> > and truncate it to the last full argument.
> >
> > This is what efi already does in commit 80b1bfe1cb2f ("efi/libstub:
> > Don't parse overlong command lines").
> >
> > Reported-by: Dmitry Vyukov <dvyukov@google.com>
> > Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> > ---
> >   drivers/of/fdt.c | 21 ++++++++++++++++++++-
> >   1 file changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> > index dcc1dd96911a..de4c6f9bac39 100644
> > --- a/drivers/of/fdt.c
> > +++ b/drivers/of/fdt.c
> > @@ -25,6 +25,7 @@
> >   #include <linux/serial_core.h>
> >   #include <linux/sysfs.h>
> >   #include <linux/random.h>
> > +#include <linux/ctype.h>
> >
> >   #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
> >   #include <asm/page.h>
> > @@ -1050,9 +1051,27 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
> >
> >       /* Retrieve command line */
> >       p = of_get_flat_dt_prop(node, "bootargs", &l);
> > -     if (p != NULL && l > 0)
> > +     if (p != NULL && l > 0) {
> >               strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
> >
> > +             /*
> > +              * If the given command line size is larger than
> > +              * COMMAND_LINE_SIZE, truncate it to the last complete
> > +              * parameter.
> > +              */
> > +             if (l > COMMAND_LINE_SIZE) {
> > +                     char *cmd_p = (char *)data + COMMAND_LINE_SIZE - 1;
> > +
> > +                     while (!isspace(*cmd_p))
> > +                             cmd_p--;
> > +
> > +                     *cmd_p = '\0';
> > +
> > +                     pr_err("Command line is too long: truncated to %d bytes\n",
> > +                            (int)(cmd_p - (char *)data + 1));
> > +             }
> > +     }
> > +
> >       /*
> >        * CONFIG_CMDLINE is meant to be a default in case nothing else
> >        * managed to set the command line, unless CONFIG_CMDLINE_FORCE
> >
>
> Any thought about that ?

It looks fine to me, but this will need to be adapted to the generic
command line support[1][2] when that is merged. So I've been waiting
to see if that's going to happen this cycle.

Rob

[1] https://lore.kernel.org/lkml/cover.1616765869.git.christophe.leroy@csgroup.eu/
[2] https://lore.kernel.org/lkml/41021d66db2ab427c14255d2a24bb4517c8b58fd.1617126961.git.danielwa@cisco.com/

Re: [PATCH] driver: of: Properly truncate command line if too long

[Alex Ghiti]

Le 4/6/21 à 9:40 AM, Rob Herring a écrit :
> On Sat, Apr 3, 2021 at 7:09 AM Alex Ghiti <alex@ghiti.fr> wrote:
>>
>> Hi,
>>
>> Le 3/16/21 à 3:38 PM, Alexandre Ghiti a écrit :
>>> In case the command line given by the user is too long, warn about it
>>> and truncate it to the last full argument.
>>>
>>> This is what efi already does in commit 80b1bfe1cb2f ("efi/libstub:
>>> Don't parse overlong command lines").
>>>
>>> Reported-by: Dmitry Vyukov <dvyukov@google.com>
>>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>>> ---
>>>    drivers/of/fdt.c | 21 ++++++++++++++++++++-
>>>    1 file changed, 20 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>>> index dcc1dd96911a..de4c6f9bac39 100644
>>> --- a/drivers/of/fdt.c
>>> +++ b/drivers/of/fdt.c
>>> @@ -25,6 +25,7 @@
>>>    #include <linux/serial_core.h>
>>>    #include <linux/sysfs.h>
>>>    #include <linux/random.h>
>>> +#include <linux/ctype.h>
>>>
>>>    #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
>>>    #include <asm/page.h>
>>> @@ -1050,9 +1051,27 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>>>
>>>        /* Retrieve command line */
>>>        p = of_get_flat_dt_prop(node, "bootargs", &l);
>>> -     if (p != NULL && l > 0)
>>> +     if (p != NULL && l > 0) {
>>>                strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
>>>
>>> +             /*
>>> +              * If the given command line size is larger than
>>> +              * COMMAND_LINE_SIZE, truncate it to the last complete
>>> +              * parameter.
>>> +              */
>>> +             if (l > COMMAND_LINE_SIZE) {
>>> +                     char *cmd_p = (char *)data + COMMAND_LINE_SIZE - 1;
>>> +
>>> +                     while (!isspace(*cmd_p))
>>> +                             cmd_p--;
>>> +
>>> +                     *cmd_p = '\0';
>>> +
>>> +                     pr_err("Command line is too long: truncated to %d bytes\n",
>>> +                            (int)(cmd_p - (char *)data + 1));
>>> +             }
>>> +     }
>>> +
>>>        /*
>>>         * CONFIG_CMDLINE is meant to be a default in case nothing else
>>>         * managed to set the command line, unless CONFIG_CMDLINE_FORCE
>>>
>>
>> Any thought about that ?
> 
> It looks fine to me, but this will need to be adapted to the generic
> command line support[1][2] when that is merged. So I've been waiting
> to see if that's going to happen this cycle.

Ok I'll take a look then, thanks.

Alex

> 
> Rob
> 
> [1] https://lore.kernel.org/lkml/cover.1616765869.git.christophe.leroy@csgroup.eu/
> [2] https://lore.kernel.org/lkml/41021d66db2ab427c14255d2a24bb4517c8b58fd.1617126961.git.danielwa@cisco.com/
> 

Re: [PATCH] driver: of: Properly truncate command line if too long

[Alex Ghiti]

Hi Andy,

Le 4/6/21 à 6:56 PM, Andy Shevchenko a écrit :
> 
> 
> On Tuesday, March 16, 2021, Alexandre Ghiti <alex@ghiti.fr 
> <mailto:alex@ghiti.fr>> wrote:
> 
>     In case the command line given by the user is too long, warn about it
>     and truncate it to the last full argument.
> 
>     This is what efi already does in commit 80b1bfe1cb2f ("efi/libstub:
>     Don't parse overlong command lines").
> 
>     Reported-by: Dmitry Vyukov <dvyukov@google.com
>     <mailto:dvyukov@google.com>>
>     Signed-off-by: Alexandre Ghiti <alex@ghiti.fr <mailto:alex@ghiti.fr>>
>     ---
>       drivers/of/fdt.c | 21 ++++++++++++++++++++-
>       1 file changed, 20 insertions(+), 1 deletion(-)
> 
>     diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>     index dcc1dd96911a..de4c6f9bac39 100644
>     --- a/drivers/of/fdt.c
>     +++ b/drivers/of/fdt.c
>     @@ -25,6 +25,7 @@
>       #include <linux/serial_core.h>
>       #include <linux/sysfs.h>
>       #include <linux/random.h>
>     +#include <linux/ctype.h>
> 
>       #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
>       #include <asm/page.h>
>     @@ -1050,9 +1051,27 @@ int __init early_init_dt_scan_chosen(unsigned
>     long node, const char *uname,
> 
>              /* Retrieve command line */
>              p = of_get_flat_dt_prop(node, "bootargs", &l);
>     -       if (p != NULL && l > 0)
>     +       if (p != NULL && l > 0) {
>                      strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
> 
>     +               /*
>     +                * If the given command line size is larger than
>     +                * COMMAND_LINE_SIZE, truncate it to the last complete
>     +                * parameter.
>     +                */
>     +               if (l > COMMAND_LINE_SIZE) {
>     +                       char *cmd_p = (char *)data +
>     COMMAND_LINE_SIZE - 1;
>     +
>     +                       while (!isspace(*cmd_p))
>     +                               cmd_p--;
> 
> 
> Shouldn’t you check for cmd_p being always bigger than or equal to data?

Yes you're right.

> 
>     +
>     +                       *cmd_p = '\0';
>     +
>     +                       pr_err("Command line is too long: truncated
>     to %d bytes\n",
>     +                              (int)(cmd_p - (char *)data + 1));
> 
> 
> Do you really need that casting?

No, I can use %td to print a pointer difference.

I'll send a v2.

Thanks,

Alex

> 
>     +               }
>     +       }
>     +
>              /*
>               * CONFIG_CMDLINE is meant to be a default in case nothing else
>               * managed to set the command line, unless CONFIG_CMDLINE_FORCE
>     -- 
>     2.20.1
> 
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>