[PATCH] init: Fix crash observed if there is no initial console

[Guenter Roeck]

Systems with no initial console crash in f_dupfd(). This happens because
console_on_rootfs() was changed to call filp_open(). Its return value
(a file pointer) is checked against NULL, but returns an ERR_PTR after
errors. This ERR_PTR is then passed as file parameter to f_dupfd(),
which experiences a severe case of indigestion.

Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Fixes: 8243186f0cc7 ("fs: remove ksys_dup()"),
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
 init/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index ec3a1463ac69..1ecfd43ed464 100644
--- a/init/main.c
+++ b/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 */
-- 
2.17.1