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SubjectRe: [PATCH] tee: check shm references are consistent in offset/size
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On 04/27/2018 06:53 AM, Etienne Carriere wrote:
> This change prevents userland from referencing TEE shared memory
> outside the area initially allocated by its owner. Prior this change an
> application could not reference or access memory it did not own but
> it could reference memory not explicitly allocated by owner.
>
> Reported-by: Alexandre Jutras <alexandre.jutras@nxp.com>
> Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
>
> ---
> drivers/tee/tee_core.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> index 0124a91..dd46b75 100644
> --- a/drivers/tee/tee_core.c
> +++ b/drivers/tee/tee_core.c
> @@ -238,6 +238,17 @@ static int params_from_user(struct tee_context
> *ctx, struct tee_param *params,

Those 2 lines above should be only one line.

> if (IS_ERR(shm))
> return PTR_ERR(shm);
>
> + /*
> + * Ensure offset + size does not overflow offset
> + * and does not overflow the size of the referred
> + * shared memory object.
> + */
> + if ((ip.a + ip.b) < ip.a ||
> + (ip.a + ip.b) > shm->size) {
> + tee_shm_put(shm);
> + return -EINVAL;
> + }
> +

Hi,
The patch makes sense but the whitespace and indentation are all mucked up.
Could be your email client.
Please check/fix and test by emailing it to yourself.

> params[n].u.memref.shm_offs = ip.a;
> params[n].u.memref.size = ip.b;
> params[n].u.memref.shm = shm;
>

thanks,
--
~Randy

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