[PATCH] media: dvb_frontend: Fix uninitialized error in dvb_frontend_handle_ioctl()

[PATCH] media: dvb_frontend: Fix uninitialized error in dvb_frontend_handle_ioctl()

[Geert Uytterhoeven]

With gcc-4.1.2:

    drivers/media/dvb-core/dvb_frontend.c: In function ‘dvb_frontend_handle_ioctl’:
    drivers/media/dvb-core/dvb_frontend.c:2110: warning: ‘err’ may be used uninitialized in this function

Indeed, there are 13 cases where err is used initialized if one of the
dvb_frontend_ops is not implemented.

Preinitialize err to -EOPNOTSUPP like before to fix this.

Fixes: d73dcf0cdb95a47f ("media: dvb_frontend: cleanup ioctl handling logic")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 drivers/media/dvb-core/dvb_frontend.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index 3ad83359098bde79..9eff8ce60d535379 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -2107,7 +2107,7 @@ static int dvb_frontend_handle_ioctl(struct file *file,
 	struct dvb_frontend *fe = dvbdev->priv;
 	struct dvb_frontend_private *fepriv = fe->frontend_priv;
 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
-	int i, err;
+	int i, err = -ENOTSUPP;
 
 	dev_dbg(fe->dvb->device, "%s:\n", __func__);
 
-- 
2.7.4

Re: [PATCH] media: dvb_frontend: Fix uninitialized error in dvb_frontend_handle_ioctl()

[Arnd Bergmann]

On Thu, Nov 16, 2017 at 11:51 AM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> With gcc-4.1.2:
>
>     drivers/media/dvb-core/dvb_frontend.c: In function ‘dvb_frontend_handle_ioctl’:
>     drivers/media/dvb-core/dvb_frontend.c:2110: warning: ‘err’ may be used uninitialized in this function
>
> Indeed, there are 13 cases where err is used initialized if one of the
> dvb_frontend_ops is not implemented.
>
> Preinitialize err to -EOPNOTSUPP like before to fix this.
>
> Fixes: d73dcf0cdb95a47f ("media: dvb_frontend: cleanup ioctl handling logic")
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Good catch!

This one shows up on x86 allmdoconfig with gcc-4.5 or older but not gcc-4.6.

Acked-by: Arnd Bergmann <arnd@arndb.de>