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@xxxxxxxx> 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@xxxxxxxxxx>
> > > Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
> > > ---
> > >    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@xxxxxxxxxx/
> [2] https://lore.kernel.org/lkml/41021d66db2ab427c14255d2a24bb4517c8b58fd.1617126961.git.danielwa@xxxxxxxxx/