[Asterisk-code-review] res_stasis_playback: Prevent media_index from going out of bounds (asterisk[17])

[Friendly Automation]

Friendly Automation has submitted this change. ( https://gerrit.asterisk.org/c/asterisk/+/13708 )

Change subject: res_stasis_playback: Prevent media_index from going out of bounds
......................................................................

res_stasis_playback: Prevent media_index from going out of bounds

Incrementing stasis_app_playback.media_index directly in our playback
loop means that when we reach the end of our playlist the index into
the vector will be outside of the bounds of the vector.

Instead use a temporary variable and only assign when we're sure that
we are in bounds.

ASTERISK-28713 #close
Reported by: Sébastien Duthil

Change-Id: Ib53f7f156097e0607eb5871d9d78d246ed274928
---
M res/res_stasis_playback.c
1 file changed, 3 insertions(+), 1 deletion(-)

Approvals:
  Joshua Colp: Looks good to me, but someone else must approve
  Benjamin Keith Ford: Looks good to me, but someone else must approve
  George Joseph: Looks good to me, approved
  Friendly Automation: Approved for Submit



diff --git a/res/res_stasis_playback.c b/res/res_stasis_playback.c
index 4a75382..7665d5f 100644
--- a/res/res_stasis_playback.c
+++ b/res/res_stasis_playback.c
@@ -287,6 +287,7 @@
 {
 	int res;
 	long offsetms;
+	size_t index;
 
 	/* Even though these local variables look fairly pointless, they avoid
 	 * having a bunch of NULL's passed directly into
@@ -305,7 +306,8 @@
 
 	offsetms = playback->offsetms;
 
-	for (; playback->media_index < AST_VECTOR_SIZE(&playback->medias); playback->media_index++) {
+	for (index = 0; index < AST_VECTOR_SIZE(&playback->medias); index++) {
+		playback->media_index = index;
 
 		/* Set the current media to play */
 		ast_string_field_set(playback, media, AST_VECTOR_GET(&playback->medias, playback->media_index));

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Gerrit-Project: asterisk
Gerrit-Branch: 17
Gerrit-Change-Id: Ib53f7f156097e0607eb5871d9d78d246ed274928
Gerrit-Change-Number: 13708
Gerrit-PatchSet: 1
Gerrit-Owner: Sean Bright <sean.bright at gmail.com>
Gerrit-Reviewer: Benjamin Keith Ford <bford at digium.com>
Gerrit-Reviewer: Friendly Automation
Gerrit-Reviewer: George Joseph <gjoseph at digium.com>
Gerrit-Reviewer: Joshua Colp <jcolp at sangoma.com>
Gerrit-MessageType: merged
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