Re: [PATCH v6 08/22] bootconfig: init: Allow admin to use bootconfig for init command line

Masami Hiramatsu
2020-08-03T15:03:55Z

On Sat, 1 Aug 2020 22:33:18 -0400
Arvind Sankar <nivedita@alum.mit.edu> wrote:

> On Fri, Feb 07, 2020 at 02:46:03PM -0500, Steven Rostedt wrote:
> >
> > diff --git a/init/main.c b/init/main.c
> > index 491f1cdb3105..113c8244e5f0 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -142,6 +142,15 @@ static char *extra_command_line;
> > /* Extra init arguments */
> > static char *extra_init_args;
> >
> > +#ifdef CONFIG_BOOT_CONFIG
> > +/* Is bootconfig on command line? */
> > +static bool bootconfig_found;
> > +static bool initargs_found;
> > +#else
> > +# define bootconfig_found false
> > +# define initargs_found false
> > +#endif
> > +
> > static char *execute_command;
> > static char *ramdisk_execute_command;
> >
> > @@ -336,17 +345,32 @@ u32 boot_config_checksum(unsigned char *p, u32 size)
> > return ret;
> > }
> >
> > +static int __init bootconfig_params(char *param, char *val,
> > + const char *unused, void *arg)
> > +{
> > + if (strcmp(param, "bootconfig") == 0) {
> > + bootconfig_found = true;
> > + } else if (strcmp(param, "--") == 0) {
> > + initargs_found = true;
> > + }
> > + return 0;
> > +}
> > +
>
> I came across this as I was poking around some of the command line
> parsing. AFAICT, initargs_found will never be set to true here, because
> parse_args handles "--" itself by immediately returning: it doesn't
> invoke the callback for it. So you'd instead have to check the return of
> parse_args("bootconfig"...) to detect the initargs_found case.

Oops, good catch!
Does this fixes the problem?

From b078e8b02ad54aea74f8c3645fc11dd3a1cdc1e7 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Mon, 3 Aug 2020 23:57:29 +0900
Subject: [PATCH] bootconfig: Fix to find the initargs correctly

Since the parse_args() stops parsing at '--', bootconfig_params()
will never get the '--' as param and initargs_found never be true.
In the result, if we pass some init arguments via the bootconfig,
those are always appended to the kernel command line with '--'
and user will see double '--'.

To fix this correctly, check the return value of parse_args()
and set initargs_found true if the return value is not an error
but a valid address.

Fixes: f61872bb58a1 ("bootconfig: Use parse_args() to find bootconfig and '--'")
Cc: stable@vger.kernel.org
Reported-by: Arvind Sankar <nivedita@alum.mit.edu>
Suggested-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
init/main.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/init/main.c b/init/main.c
index 0ead83e86b5a..627f9230dbe8 100644
--- a/init/main.c
+++ b/init/main.c
@@ -387,8 +387,6 @@ static int __init bootconfig_params(char *param, char *val,
{
if (strcmp(param, "bootconfig") == 0) {
bootconfig_found = true;
- } else if (strcmp(param, "--") == 0) {
- initargs_found = true;
}
return 0;
}
@@ -399,19 +397,23 @@ static void __init setup_boot_config(const char *cmdline)
const char *msg;
int pos;
u32 size, csum;
- char *data, *copy;
+ char *data, *copy, *err;
int ret;

/* Cut out the bootconfig data even if we have no bootconfig option */
data = get_boot_config_from_initrd(&size, &csum);

strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
- parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
- bootconfig_params);
+ err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
+ bootconfig_params);

- if (!bootconfig_found)
+ if (IS_ERR(err) || !bootconfig_found)
return;

+ /* parse_args() stops at '--' and returns an address */
+ if (!IS_ERR(err) && err)
+ initargs_found = true;
+
if (!data) {
pr_err("'bootconfig' found on command line, but no bootconfig found\n");
return;
--
2.25.1