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.
Fixes: 99b8a5d608 ("soundwire: Add bank switch routine")
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200902202650.14189-1-trix@redhat.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
3fbbf2148a