Re: [PATCH v2] soundwire: fix double free of dangling pointer

[Vinod Koul]

On 02-09-20, 13:26, trix@xxxxxxxxxx wrote:
> From: Tom Rix <trix@xxxxxxxxxx>
> 
> clang static analysis flags this problem
> 
> stream.c:844:9: warning: Use of memory after
>   it is freed
>         kfree(bus->defer_msg.msg->buf);
>               ^~~~~~~~~~~~~~~~~~~~~~~
> 
> This happens in an error handler cleaning up memory
> allocated for elements in a list.
> 
> 	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
> 		bus = m_rt->bus;
> 
> 		kfree(bus->defer_msg.msg->buf);
> 		kfree(bus->defer_msg.msg);
> 	}
> 
> And is triggered when the call to sdw_bank_switch() fails.
> There are a two problems.
> 
> First, when sdw_bank_switch() fails, though it frees memory it
> does not clear bus's reference 'defer_msg.msg' to that memory.
> 
> The second problem is the freeing msg->buf. In some cases
> msg will be NULL so this will dereference a null pointer.
> Need to check before freeing.

Applied, thanks

-- 
~Vinod