[PATCH] soc: soc-dapm: fix two incorrect uses of list iterator

Xiaomeng Tong
2022-03-27T08:21:49Z

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 break the outer list_for_each_entry_safe()
loop if w->event is NULL, but forgot to *break* switch statement first.
So just add a break 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>
---
sound/soc/soc-dapm.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index b06c5682445c..2a5a64d21856 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -1686,9 +1686,11 @@ static void dapm_seq_run(struct snd_soc_card *card,

switch (w->id) {
case snd_soc_dapm_pre:
- if (!w->event)
+ if (!w->event) {
list_for_each_entry_safe_continue(w, n, list,
power_list);
+ break;
+ }

if (event == SND_SOC_DAPM_STREAM_START)
ret = w->event(w,
@@ -1699,9 +1701,11 @@ static void dapm_seq_run(struct snd_soc_card *card,
break;

case snd_soc_dapm_post:
- if (!w->event)
+ if (!w->event) {
list_for_each_entry_safe_continue(w, n, list,
power_list);
+ break;
+ }

if (event == SND_SOC_DAPM_STREAM_START)
ret = w->event(w,
--
2.17.1