On Wed Aug 13, 2025 at 12:52 AM CEST, Timur Tabi wrote:
> On Mon, 2025-08-11 at 17:19 +0800, Qianfeng Rong wrote:
>> Replace kfree() with kvfree() for memory allocated by kvmalloc().
>>
>> Compile-tested only.
>>
>> Signed-off-by: Qianfeng Rong <rongqianf...@vivo.com>
>
> Reviewed-by: Timur Tabi <tt...@nvidia.com>
>
> This does fix a real bug.
>
> However, I think the real problem is that it's really confusing that
> r535_gsp_msgq_recv_one_elem(gsp, &info) returns info.gsp_rpc_buf instead of
> just success/failure.
> r535_gsp_msgq_recv() does this:
>
> buf = kvmalloc(max_t(u32, rpc->length, expected), GFP_KERNEL);
> ...
> info.gsp_rpc_buf = buf;
> ...
> buf = r535_gsp_msgq_recv_one_elem(gsp, &info);
>
> You wouldn't know it, but this does not change the value of 'buf' unless
> r535_gsp_msgq_recv_one_elem() fails. If it does fail, the code does this:
Ick! That makes no sense, r535_gsp_msgq_recv_one_elem() should just return an
int and we shouldn't overwrite buf -- that's a footgun.
> if (IS_ERR(buf)) {
> kvfree(info.gsp_rpc_buf);
Should just be
if (ret) {
kvfree(buf);
return ERR_PTR(ret);
}
It also doesn't need the info.gsp_rpc_buf = NULL; assignment, info is local
anyways.
> It would be a lot clearer if we could kvfree(buf) here, but we can't because
> 'buf' no longer points
> to the buffer, even though the buffer still exists.
Agreed.
Zhi, Timur do you want to send a follow-up patch for this?
