As I'm not an expert for the fastrpc driver, I'm not sure about the patch code.
But I think the bug should be patched.
Please suggest a proper patch.
Best regards,
2023년 2월 16일 (목) 오전 10:41, Sangsup Lee <k1rh4.lee@xxxxxxxxx>님이 작성:
>
> This patch adds mutex_lock for fixing an Use-after-free bug.
> fastrpc_req_munmap_impl can be called concurrently in multi-threded environments.
> The buf which is allocated by list_for_each_safe can be used after another thread frees it.
>
> Signed-off-by: Sangsup Lee <k1rh4.lee@xxxxxxxxx>
> ---
> drivers/misc/fastrpc.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 5310606113fe..c4b5fa4a50a6 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -1806,10 +1806,12 @@ static int fastrpc_req_munmap(struct fastrpc_user *fl, char __user *argp)
> struct fastrpc_buf *buf = NULL, *iter, *b;
> struct fastrpc_req_munmap req;
> struct device *dev = fl->sctx->dev;
> + int err;
>
> if (copy_from_user(&req, argp, sizeof(req)))
> return -EFAULT;
>
> + mutex_lock(&fl->mutex);
> spin_lock(&fl->lock);
> list_for_each_entry_safe(iter, b, &fl->mmaps, node) {
> if ((iter->raddr == req.vaddrout) && (iter->size == req.size)) {
> @@ -1822,10 +1824,13 @@ static int fastrpc_req_munmap(struct fastrpc_user *fl, char __user *argp)
> if (!buf) {
> dev_err(dev, "mmap\t\tpt 0x%09llx [len 0x%08llx] not in list\n",
> req.vaddrout, req.size);
> + mutex_unlock(&fl->mutex);
> return -EINVAL;
> }
>
> - return fastrpc_req_munmap_impl(fl, buf);
> + err = fastrpc_req_munmap_impl(fl, buf);
> + mutex_unlock(&fl->mutex);
> + return err;
> }
>
> static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
> --
> 2.25.1
>
