[PATCH (repost)] Input: MT - use __GFP_NOWARN allocation at input_mt_init_slots()

[PATCH (repost)] Input: MT - use __GFP_NOWARN allocation at input_mt_init_slots()

[Tetsuo Handa]

syzbot is reporting too large allocation at input_mt_init_slots(), for
num_slots is supplied from userspace using ioctl(UI_DEV_CREATE).

Use __GFP_NOWARN. Also, replace n2 with array_size(), for 32bits variable
n2 will overflow if num_slots >= 65536 and will cause out of bounds
read/write at input_mt_set_matrix()/input_mt_set_slots() on architectures
where PAGE_SIZE > 4096 is available (e.g. PPC64).

Reported-by: syzbot <syzbot+0122fa359a69694395d5@syzkaller.appspotmail.com>
Link: https://syzkaller.appspot.com/bug?extid=0122fa359a69694395d5
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
Dmitry Torokhov proposed limiting max size to accept. But since it seems
that nobody knows appropriate max size to accept, reposting as-is.
https://lkml.kernel.org/r/03e8c3f0-bbbf-af37-6f52-67547cbd4cde@I-love.SAKURA.ne.jp

 drivers/input/input-mt.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
index 14b53dac1253..cf74579462ba 100644
--- a/drivers/input/input-mt.c
+++ b/drivers/input/input-mt.c
@@ -47,7 +47,7 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
 	if (mt)
 		return mt->num_slots != num_slots ? -EINVAL : 0;
 
-	mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL);
+	mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL | __GFP_NOWARN);
 	if (!mt)
 		goto err_mem;
 
@@ -80,8 +80,8 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
 	if (flags & INPUT_MT_SEMI_MT)
 		__set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
 	if (flags & INPUT_MT_TRACK) {
-		unsigned int n2 = num_slots * num_slots;
-		mt->red = kcalloc(n2, sizeof(*mt->red), GFP_KERNEL);
+		mt->red = kcalloc(array_size(num_slots, num_slots),
+				  sizeof(*mt->red), GFP_KERNEL | __GFP_NOWARN);
 		if (!mt->red)
 			goto err_mem;
 	}
-- 
2.18.4

Re: [PATCH (repost)] Input: MT - use __GFP_NOWARN allocation at input_mt_init_slots()

[Tetsuo Handa]

Ping?

On 2023/03/28 20:25, Tetsuo Handa wrote:
> syzbot is reporting too large allocation at input_mt_init_slots(), for
> num_slots is supplied from userspace using ioctl(UI_DEV_CREATE).
> 
> Use __GFP_NOWARN. Also, replace n2 with array_size(), for 32bits variable
> n2 will overflow if num_slots >= 65536 and will cause out of bounds
> read/write at input_mt_set_matrix()/input_mt_set_slots() on architectures
> where PAGE_SIZE > 4096 is available (e.g. PPC64).
> 
> Reported-by: syzbot <syzbot+0122fa359a69694395d5@syzkaller.appspotmail.com>
> Link: https://syzkaller.appspot.com/bug?extid=0122fa359a69694395d5
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
> Dmitry Torokhov proposed limiting max size to accept. But since it seems
> that nobody knows appropriate max size to accept, reposting as-is.
> https://lkml.kernel.org/r/03e8c3f0-bbbf-af37-6f52-67547cbd4cde@I-love.SAKURA.ne.jp
> 
>  drivers/input/input-mt.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
> index 14b53dac1253..cf74579462ba 100644
> --- a/drivers/input/input-mt.c
> +++ b/drivers/input/input-mt.c
> @@ -47,7 +47,7 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
>  	if (mt)
>  		return mt->num_slots != num_slots ? -EINVAL : 0;
>  
> -	mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL);
> +	mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL | __GFP_NOWARN);
>  	if (!mt)
>  		goto err_mem;
>  
> @@ -80,8 +80,8 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
>  	if (flags & INPUT_MT_SEMI_MT)
>  		__set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
>  	if (flags & INPUT_MT_TRACK) {
> -		unsigned int n2 = num_slots * num_slots;
> -		mt->red = kcalloc(n2, sizeof(*mt->red), GFP_KERNEL);
> +		mt->red = kcalloc(array_size(num_slots, num_slots),
> +				  sizeof(*mt->red), GFP_KERNEL | __GFP_NOWARN);
>  		if (!mt->red)
>  			goto err_mem;
>  	}

Re: [PATCH (repost)] Input: MT - use __GFP_NOWARN allocation at input_mt_init_slots()

[Greg Kroah-Hartman]

On Sun, Sep 03, 2023 at 10:55:45PM +0900, Tetsuo Handa wrote:
> Ping?
> 
> On 2023/03/28 20:25, Tetsuo Handa wrote:

It's the middle of the merge window, no one can do anything until after
-rc1 is out, you know this...

greg k-h