On Thu, Jun 09, 2022 at 02:45:18PM -0700, Jared Kangas wrote:
gbaudio_dapm_free_controls() iterates over widgets using the list_for_each_entry*() family of macros from <linux/list.h>, which leaves the loop cursor pointing to a meaningless structure if it completes a traversal of the list. The cursor was set to NULL at the end of the loop body, but would be overwritten by the final loop cursor update.
Because of this behavior, the widget could be non-null after the loop even if the widget wasn't found, and the cleanup logic would treat the pointer as a valid widget to free.
To fix this, introduce a temporary variable to act as the loop cursor and copy it to a variable that can be accessed after the loop finishes. Due to not removing any list elements, use list_for_each_entry() instead of list_for_each_entry_safe() in the revised loop.
This was detected with the help of Coccinelle.
Fixes: 510e340efe0c ("staging: greybus: audio: Add helper APIs for dynamic audio modules") Cc: stable@vger.kernel.org Reviewed-by: Dan Carpenter dan.carpenter@oracle.com Reviewed-by: Johan Hovold johan@kernel.org Signed-off-by: Jared Kangas kangas.jd@gmail.com
Changes since v1:
- Removed safe list iteration as suggested by Johan Hovold johan@kernel.org
- Updated patch changelog to explain the list iteration change
- Added tags to changelog based on feedback (Cc:, Fixes:, Reviewed-by:)
drivers/staging/greybus/audio_helper.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/staging/greybus/audio_helper.c b/drivers/staging/greybus/audio_helper.c index 843760675876..05e91e6bc2a0 100644 --- a/drivers/staging/greybus/audio_helper.c +++ b/drivers/staging/greybus/audio_helper.c @@ -115,7 +115,7 @@ int gbaudio_dapm_free_controls(struct snd_soc_dapm_context *dapm, int num) { int i;
- struct snd_soc_dapm_widget *w, *next_w;
- struct snd_soc_dapm_widget *w, *tmp_w;
#ifdef CONFIG_DEBUG_FS struct dentry *parent = dapm->debugfs_dapm; struct dentry *debugfs_w = NULL; @@ -124,13 +124,13 @@ int gbaudio_dapm_free_controls(struct snd_soc_dapm_context *dapm, mutex_lock(&dapm->card->dapm_mutex); for (i = 0; i < num; i++) { /* below logic can be optimized to identify widget pointer */
list_for_each_entry_safe(w, next_w, &dapm->card->widgets,list) {if (w->dapm != dapm)continue;if (!strcmp(w->name, widget->name))
w = NULL;list_for_each_entry(tmp_w, &dapm->card->widgets, list) {if (tmp_w->dapm == dapm &&!strcmp(tmp_w->name, widget->name)) {w = tmp_w; break;
w = NULL;
}-- 2.34.3
Hi,
This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him a patch that has triggered this response. He used to manually respond to these common problems, but in order to save his sanity (he kept writing the same thing over and over, yet to different people), I was created. Hopefully you will not take offence and will fix the problem in your patch and resubmit it so that it can be accepted into the Linux kernel tree.
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