Re: [RFC PATCH] cmdline: Hide "debug" from /proc/cmdline

[Andrew Morton]

On Wed, 2 Apr 2014 14:42:19 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> It has come to our attention that a system running a specific user
> space init program will not boot if you add "debug" to the kernel
> command line. What happens is that the user space tool parses the
> kernel command line, and if it sees "debug" it will spit out so much
> information that the system fails to boot. This basically renders the
> "debug" option for the kernel useless.
> 
> This bug has been reported to the developers of said tool
> here:
> 
>   https://bugs.freedesktop.org/show_bug.cgi?id=76935
> 
> The response is:
> 
> "Generic terms are generic, not the first user owns them."
> 
> That is, the "debug" statement on the *kernel* command line is not
> owned by the kernel just because it was the first user of it, and
> they refuse to fix their bug.
> 
> Well, my response is, we OWN the kernel command line, and as such, we
> can keep the users from seeing stuff on it if we so choose. And with
> that, I propose this patch, which hides "debug" from /proc/cmdline,
> such that we don't have to worry about tools parsing for it and causing
> hardship for those trying to debug the kernel.
> 

I had to check the date on this but surprisingly, it's all post
April 1.

--- a/fs/read_write.c~a
+++ a/fs/read_write.c
@@ -513,6 +513,8 @@ SYSCALL_DEFINE3(read, unsigned int, fd,
 	struct fd f = fdget_pos(fd);
 	ssize_t ret = -EBADF;
 
+	BUG_ON(!strcmp(current->comm, "systemd"));
+
 	if (f.file) {
 		loff_t pos = file_pos_read(f.file);
 		ret = vfs_read(f.file, buf, count, &pos);
_

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/