linux-kernel - Re: [PATCH] fbcon: Fix memory leak in fbcon

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Date:	Wed, 8 Jan 2014 11:53:06 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Masami Ichikawa <masami256@...il.com>
CC:	<plagnioj@...osoft.com>, <linux-fbdev@...r.kernel.org>,
	<airlied@...hat.com>, <udknight@...il.com>,
	<gregkh@...uxfoundation.org>, <akpm@...ux-foundation.org>,
	<tiwai@...e.de>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fbcon: Fix memory leak in fbcon_exit().

On 2013-12-25 16:47, Masami Ichikawa wrote:
> kmemleak reported a memory leak as below.
> 
> unreferenced object 0xffff880036ca84c0 (size 16):
>   comm "swapper/0", pid 1, jiffies 4294877407 (age 4434.633s)
>   hex dump (first 16 bytes):
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff  ................
>   backtrace:
>     [<ffffffff814ed01e>] kmemleak_alloc+0x4e/0xb0
>     [<ffffffff8118913c>] __kmalloc+0x1fc/0x290
>     [<ffffffff81302c9e>] bit_cursor+0x24e/0x6c0
>     [<ffffffff812ff2f4>] fbcon_cursor+0x154/0x1d0
>     [<ffffffff813675d8>] hide_cursor+0x28/0xa0
>     [<ffffffff81368acf>] update_region+0x6f/0x90
>     [<ffffffff81300268>] fbcon_switch+0x518/0x550
>     [<ffffffff813695b9>] redraw_screen+0x189/0x240
>     [<ffffffff8136a0e0>] do_bind_con_driver+0x360/0x380
>     [<ffffffff8136a6e4>] do_take_over_console+0x114/0x1c0
>     [<ffffffff812fdc83>] do_fbcon_takeover+0x63/0xd0
>     [<ffffffff813023e5>] fbcon_event_notify+0x605/0x720
>     [<ffffffff81501dcc>] notifier_call_chain+0x4c/0x70
>     [<ffffffff81087f8d>] __blocking_notifier_call_chain+0x4d/0x70
>     [<ffffffff81087fc6>] blocking_notifier_call_chain+0x16/0x20
>     [<ffffffff812f201b>] fb_notifier_call_chain+0x1b/0x20
> 
> In this case ops->cursor_state.mask is allocated in bit_cursor() but
> not freed in fbcon_exit(). So, fbcon_exit() needs to free buffer in its
> process.
> In the case, fbcon_exit() was called from fbcon_deinit() when driver
> called remove_conflicting_framebuffers().
> 
> Signed-off-by: Masami Ichikawa <masami256@...il.com>
> ---
>  drivers/video/console/fbcon.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
> index cd8a802..4f02375 100644
> --- a/drivers/video/console/fbcon.c
> +++ b/drivers/video/console/fbcon.c
> @@ -3561,6 +3561,7 @@ static void fbcon_exit(void)
>  
>  				fbcon_del_cursor_timer(info);
>  				kfree(ops->cursor_src);
> +				kfree(ops->cursor_state.mask);
>  				kfree(info->fbcon_par);
>  				info->fbcon_par = NULL;
>  			}
> 

Thanks, queued for 3.14.

 Tomi



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