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

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