On Fri, Dec 22, 2017 at 6:51 PM, Colin King <colin.king@xxxxxxxxxxxxx> wrote:
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> In the case that shm->pages fails to allocate, the current exit
> error path will try to put_page on a null shm->pages and cause
> a null pointer dereference when accessing shm->pages[n]. Fix this
> by only performing the put_page and kfree on shm->pages if it
> is not null.
>
> Detected by CoverityScan, CID#1463283 ("Dereference after null check")
>
> Fixes: 033ddf12bcf5 ("tee: add register user memory")
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> ---
> drivers/tee/tee_shm.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 13b4de1157c7..6890c8aaef8c 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -335,9 +335,11 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> idr_remove(&teedev->idr, shm->id);
> mutex_unlock(&teedev->mutex);
> }
> - for (n = 0; n < shm->num_pages; n++)
> - put_page(shm->pages[n]);
> - kfree(shm->pages);
> + if (shm->pages) {
> + for (n = 0; n < shm->num_pages; n++)
> + put_page(shm->pages[n]);
> + kfree(shm->pages);
> + }
> }
> kfree(shm);
> teedev_ctx_put(ctx);
> --
> 2.14.1
>
Looks good. Thanks.
/Jens
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