early init: fix error handling when opening /dev/console

The comment says "this should never fail", but it definitely can fail
when you have odd initial boot filesystems, or kernel configurations.

So get the error handling right: filp_open() returns an error pointer.

Reported-by: Jesse Barnes <[email protected]>
Reported-by: youling 257 <[email protected]>
Fixes: 8243186f0c ("fs: remove ksys_dup()")
Cc: Dominik Brodowski <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

init/main.c

@@ -1163,7 +1163,7 @@ void console_on_rootfs(void)
 
 	/* Open /dev/console in kernelspace, this should never fail */
 	file = filp_open("/dev/console", O_RDWR, 0);
-	if (!file)
+	if (IS_ERR(file))
 		goto err_out;
 
 	/* create stdin/stdout/stderr, this should never fail */