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SubjectRe: [PATCH RFC] serio HIL MLC: don't deref null, don't leak and return proper error
On Sun, Nov 07, 2010 at 08:36:33PM +0100, Jesper Juhl wrote:
> Hi,
>
> While reviewing various users of kernel memory allocation functions I came
> across drivers/input/serio/hil_mlc.c::hil_mlc_register() and noticed that
> - it calls kzalloc() buf fails to check for a NULL return before use.
> - it makes several allocations and if one fails it doesn't free the
> previous ones.
> - It doesn't return -ENOMEM in the failed memory allocation case (it just
> crashes).
> This patch corrects all of the above and also reworks the only caller of
> this function that I could find
> (drivers/input/serio/hp_sdc_mlc.c::hp_sdc_mlc_out()) so that it now checks
> the return value of hil_mlc_register() and properly propagate it on
> failure and I also restructured the code to remove some labels and goto's
> to make it, IMHO nicer to read.
>
> I have no hardware to test, so please review carefully and let me know if
> I've done something completely stupid. Please don't merge this RFC patch
> unless at least one or more people who know this code and can actually
> test it have ACK'ed it.

I think Helge Deller (CCed) used to have access to such hardware...

>
> Ohh and please do CC me on replies.
>
>
> Signed-off-by: Jesper Juhl <jj@chaosbits.net>
> ---
> hil_mlc.c | 5 +++++
> hp_sdc_mlc.c | 18 +++++++++---------
> 2 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/input/serio/hil_mlc.c b/drivers/input/serio/hil_mlc.c
> index e5624d8..bfd3865 100644
> --- a/drivers/input/serio/hil_mlc.c
> +++ b/drivers/input/serio/hil_mlc.c
> @@ -932,6 +932,11 @@ int hil_mlc_register(hil_mlc *mlc)
> hil_mlc_copy_di_scratch(mlc, i);
> mlc_serio = kzalloc(sizeof(*mlc_serio), GFP_KERNEL);
> mlc->serio[i] = mlc_serio;
> + if (!mlc->serio[i]) {
> + for (; i >= 0; i--)
> + kfree(mlc->serio[i]);
> + return -ENOMEM;
> + }
> snprintf(mlc_serio->name, sizeof(mlc_serio->name)-1, "HIL_SERIO%d", i);
> snprintf(mlc_serio->phys, sizeof(mlc_serio->phys)-1, "HIL%d", i);
> mlc_serio->id = hil_mlc_serio_id;
> diff --git a/drivers/input/serio/hp_sdc_mlc.c b/drivers/input/serio/hp_sdc_mlc.c
> index 7d2b820..d50f067 100644
> --- a/drivers/input/serio/hp_sdc_mlc.c
> +++ b/drivers/input/serio/hp_sdc_mlc.c
> @@ -305,6 +305,7 @@ static void hp_sdc_mlc_out(hil_mlc *mlc)
> static int __init hp_sdc_mlc_init(void)
> {
> hil_mlc *mlc = &hp_sdc_mlc;
> + int err;
>
> #ifdef __mc68000__
> if (!MACH_IS_HP300)
> @@ -323,22 +324,21 @@ static int __init hp_sdc_mlc_init(void)
> mlc->out = &hp_sdc_mlc_out;
> mlc->priv = &hp_sdc_mlc_priv;
>
> - if (hil_mlc_register(mlc)) {
> + err = hil_mlc_register(mlc);
> + if (err) {
> printk(KERN_WARNING PREFIX "Failed to register MLC structure with hil_mlc\n");
> - goto err0;
> + return err;
> }
>
> if (hp_sdc_request_hil_irq(&hp_sdc_mlc_isr)) {
> printk(KERN_WARNING PREFIX "Request for raw HIL ISR hook denied\n");
> - goto err1;
> + if (hil_mlc_unregister(mlc))
> + printk(KERN_ERR PREFIX "Failed to unregister MLC structure with hil_mlc.\n"
> + "This is bad. Could cause an oops.\n");
> + return -EBUSY;
> }
> +
> return 0;
> - err1:
> - if (hil_mlc_unregister(mlc))
> - printk(KERN_ERR PREFIX "Failed to unregister MLC structure with hil_mlc.\n"
> - "This is bad. Could cause an oops.\n");
> - err0:
> - return -EBUSY;
> }
>
> static void __exit hp_sdc_mlc_exit(void)
>
>
>
> --
> Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
> Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
> Plain text mails only, please.
>

--
Dmitry


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