From: Jens Wiklander <jens.wiklander@linaro.org>

commit 573ae4f13f630d6660008f1974c0a8a29c30e18a upstream.

With special lengths supplied by user space, register_shm_helper() has
an integer overflow when calculating the number of pages covered by a
supplied user space memory region.

This causes internal_get_user_pages_fast() a helper function of
pin_user_pages_fast() to do a NULL pointer dereference:

  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
  Modules linked in:
  CPU: 1 PID: 173 Comm: optee_example_a Not tainted 5.19.0 #11
  Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
  pc : internal_get_user_pages_fast+0x474/0xa80
  Call trace:
   internal_get_user_pages_fast+0x474/0xa80
   pin_user_pages_fast+0x24/0x4c
   register_shm_helper+0x194/0x330
   tee_shm_register_user_buf+0x78/0x120
   tee_ioctl+0xd0/0x11a0
   __arm64_sys_ioctl+0xa8/0xec
   invoke_syscall+0x48/0x114

Fix this by adding an an explicit call to access_ok() in
tee_shm_register_user_buf() to catch an invalid user space address
early.

Fixes: 033ddf12bcf5 ("tee: add register user memory")
Cc: stable@vger.kernel.org
Reported-by: Nimish Mishra <neelam.nimish@gmail.com>
Reported-by: Anirban Chakraborty <ch.anirban00727@gmail.com>
Reported-by: Debdeep Mukhopadhyay <debdeep.mukhopadhyay@gmail.com>
Suggested-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tee/tee_shm.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -222,6 +222,9 @@ struct tee_shm *tee_shm_register(struct
 		goto err;
 	}
 
+	if (!access_ok((void __user *)addr, length))
+		return ERR_PTR(-EFAULT);
+
 	mutex_lock(&teedev->mutex);
 	shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
 	mutex_unlock(&teedev->mutex);

Hi!

> From: Jens Wiklander <jens.wiklander@linaro.org>
> 
> commit 573ae4f13f630d6660008f1974c0a8a29c30e18a upstream.
> 
> With special lengths supplied by user space, register_shm_helper() has
> an integer overflow when calculating the number of pages covered by a
> supplied user space memory region.
> 
> This causes internal_get_user_pages_fast() a helper function of
> pin_user_pages_fast() to do a NULL pointer dereference:

Maybe this needs fixing, but this fix adds a memory leak or two. Note
the goto err, that needs to be done.

Best regards,
								Pavel

Signed-off-by: Pavel Machek <pavel@denx.de>

> +++ b/drivers/tee/tee_shm.c
> @@ -222,6 +222,9 @@ struct tee_shm *tee_shm_register(struct
>  		goto err;
>  	}
>  
> +	if (!access_ok((void __user *)addr, length))
> +		return ERR_PTR(-EFAULT);
> +
>  	mutex_lock(&teedev->mutex);
>  	shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
>  	mutex_unlock(&teedev->mutex);
> 


diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 6e662fb131d5..283fa50676a2 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -222,8 +222,10 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 		goto err;
 	}
 
-	if (!access_ok((void __user *)addr, length))
-		return ERR_PTR(-EFAULT);
+	if (!access_ok((void __user *)addr, length)) {
+		ret = ERR_PTR(-EFAULT);
+		goto err;
+	}
 
 	mutex_lock(&teedev->mutex);
 	shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

Hi,

On Mon, Aug 22, 2022 at 1:15 PM Pavel Machek <pavel@denx.de> wrote:
>
> Hi!
>
> > From: Jens Wiklander <jens.wiklander@linaro.org>
> >
> > commit 573ae4f13f630d6660008f1974c0a8a29c30e18a upstream.
> >
> > With special lengths supplied by user space, register_shm_helper() has
> > an integer overflow when calculating the number of pages covered by a
> > supplied user space memory region.
> >
> > This causes internal_get_user_pages_fast() a helper function of
> > pin_user_pages_fast() to do a NULL pointer dereference:
>
> Maybe this needs fixing, but this fix adds a memory leak or two. Note
> the goto err, that needs to be done.

Thanks for bringing this up. I believe the best option is to take the
backport I just did for 5.4, it should apply cleanly on the 5.10
stable kernel too.

Greg,  can you cherry-pick the 5.4 backport patch, or would you rather
have an explicit backport for this stable kernel?

Cheers,
Jens

>
> Best regards,
>                                                                 Pavel
>
> Signed-off-by: Pavel Machek <pavel@denx.de>
>
> > +++ b/drivers/tee/tee_shm.c
> > @@ -222,6 +222,9 @@ struct tee_shm *tee_shm_register(struct
> >               goto err;
> >       }
> >
> > +     if (!access_ok((void __user *)addr, length))
> > +             return ERR_PTR(-EFAULT);
> > +
> >       mutex_lock(&teedev->mutex);
> >       shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
> >       mutex_unlock(&teedev->mutex);
> >
>
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 6e662fb131d5..283fa50676a2 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -222,8 +222,10 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>                 goto err;
>         }
>
> -       if (!access_ok((void __user *)addr, length))
> -               return ERR_PTR(-EFAULT);
> +       if (!access_ok((void __user *)addr, length)) {
> +               ret = ERR_PTR(-EFAULT);
> +               goto err;
> +       }
>
>         mutex_lock(&teedev->mutex);
>         shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
>
> --
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

On Mon, Aug 22, 2022 at 3:03 PM Jens Wiklander
<jens.wiklander@linaro.org> wrote:
>
> Hi,
>
> On Mon, Aug 22, 2022 at 1:15 PM Pavel Machek <pavel@denx.de> wrote:
> >
> > Hi!
> >
> > > From: Jens Wiklander <jens.wiklander@linaro.org>
> > >
> > > commit 573ae4f13f630d6660008f1974c0a8a29c30e18a upstream.
> > >
> > > With special lengths supplied by user space, register_shm_helper() has
> > > an integer overflow when calculating the number of pages covered by a
> > > supplied user space memory region.
> > >
> > > This causes internal_get_user_pages_fast() a helper function of
> > > pin_user_pages_fast() to do a NULL pointer dereference:
> >
> > Maybe this needs fixing, but this fix adds a memory leak or two. Note
> > the goto err, that needs to be done.
>
> Thanks for bringing this up. I believe the best option is to take the
> backport I just did for 5.4, it should apply cleanly on the 5.10
> stable kernel too.
>
> Greg,  can you cherry-pick the 5.4 backport patch, or would you rather
> have an explicit backport for this stable kernel?

I'm sorry, I'm confused by all the backports. I haven't posted the 5.4
yet, I've only just tested it. I'll tag that backport patch for 5.10
stable too.

Thanks,
Jens

>
> Cheers,
> Jens
>
> >
> > Best regards,
> >                                                                 Pavel
> >
> > Signed-off-by: Pavel Machek <pavel@denx.de>
> >
> > > +++ b/drivers/tee/tee_shm.c
> > > @@ -222,6 +222,9 @@ struct tee_shm *tee_shm_register(struct
> > >               goto err;
> > >       }
> > >
> > > +     if (!access_ok((void __user *)addr, length))
> > > +             return ERR_PTR(-EFAULT);
> > > +
> > >       mutex_lock(&teedev->mutex);
> > >       shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
> > >       mutex_unlock(&teedev->mutex);
> > >
> >
> >
> > diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> > index 6e662fb131d5..283fa50676a2 100644
> > --- a/drivers/tee/tee_shm.c
> > +++ b/drivers/tee/tee_shm.c
> > @@ -222,8 +222,10 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> >                 goto err;
> >         }
> >
> > -       if (!access_ok((void __user *)addr, length))
> > -               return ERR_PTR(-EFAULT);
> > +       if (!access_ok((void __user *)addr, length)) {
> > +               ret = ERR_PTR(-EFAULT);
> > +               goto err;
> > +       }
> >
> >         mutex_lock(&teedev->mutex);
> >         shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
> >
> > --
> > DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany