[PATCH 4.9 18/24] ASoC: soc-dapm: fix two incorrect uses of list iterator

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Xiaomeng Tong <xiam0nd.tong@gmail.com>

commit f730a46b931d894816af34a0ff8e4ad51565b39f upstream.

These two bug are here:
	list_for_each_entry_safe_continue(w, n, list,
					power_list);
	list_for_each_entry_safe_continue(w, n, list,
					power_list);

After the list_for_each_entry_safe_continue() exits, the list iterator
will always be a bogus pointer which point to an invalid struct objdect
containing HEAD member. The funciton poniter 'w->event' will be a
invalid value which can lead to a control-flow hijack if the 'w' can be
controlled.

The original intention was to continue the outer list_for_each_entry_safe()
loop with the same entry if w->event is NULL, but misunderstanding the
meaning of list_for_each_entry_safe_continue().

So just add a 'continue;' to fix the bug.

Cc: stable@vger.kernel.org
Fixes: 163cac061c973 ("ASoC: Factor out DAPM sequence execution")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Link: https://lore.kernel.org/r/20220329012134.9375-1-xiam0nd.tong@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/soc/soc-dapm.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -1569,8 +1569,7 @@ static void dapm_seq_run(struct snd_soc_
 		switch (w->id) {
 		case snd_soc_dapm_pre:
 			if (!w->event)
-				list_for_each_entry_safe_continue(w, n, list,
-								  power_list);
+				continue;
 
 			if (event == SND_SOC_DAPM_STREAM_START)
 				ret = w->event(w,
@@ -1582,8 +1581,7 @@ static void dapm_seq_run(struct snd_soc_
 
 		case snd_soc_dapm_post:
 			if (!w->event)
-				list_for_each_entry_safe_continue(w, n, list,
-								  power_list);
+				continue;
 
 			if (event == SND_SOC_DAPM_STREAM_START)
 				ret = w->event(w,