[Asterisk-code-review] channel: Protect flags in ast waitfor nandfds operation. (asterisk[13])

[Joshua Colp]

Joshua Colp has uploaded a new change for review. ( https://gerrit.asterisk.org/4930 )

Change subject: channel: Protect flags in ast_waitfor_nandfds operation.
......................................................................

channel: Protect flags in ast_waitfor_nandfds operation.

The ast_waitfor_nandfds operation will manipulate the flags
of channels passed in. This was previously done without
the channel lock being held. This could result in incorrect
values existing for the flags if another thread manipulated
the flags at the same time.

This change locks the channel during flag manipulation.

ASTERISK-26788

Change-Id: I2c5c8edec17c9bdad4a93291576838cb552ca5ed
---
M main/channel.c
1 file changed, 6 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/30/4930/1

diff --git a/main/channel.c b/main/channel.c
index 28cfa79..fa3debf 100644
--- a/main/channel.c
+++ b/main/channel.c
@@ -3130,7 +3130,9 @@
 			fdmap[max].chan = x;  /* channel x is linked to this pfds */
 			max += ast_add_fd(&pfds[max], ast_channel_fd(c[x], y));
 		}
+		ast_channel_lock(c[x]);
 		CHECK_BLOCKING(c[x]);
+		ast_channel_unlock(c[x]);
 	}
 	/* Add the individual fds */
 	for (x = 0; x < nfds; x++) {
@@ -3157,7 +3159,9 @@
 		res = ast_poll(pfds, max, rms);
 	}
 	for (x = 0; x < n; x++) {
+		ast_channel_lock(c[x]);
 		ast_clear_flag(ast_channel_flags(c[x]), AST_FLAG_BLOCKING);
+		ast_channel_unlock(c[x]);
 	}
 	if (res < 0) { /* Simulate a timeout if we were interrupted */
 		if (errno != EINTR) {
@@ -3193,12 +3197,14 @@
 		}
 		if (fdmap[x].chan >= 0) {	/* this is a channel */
 			winner = c[fdmap[x].chan];	/* override previous winners */
+			ast_channel_lock(winner);
 			if (res & POLLPRI) {
 				ast_set_flag(ast_channel_flags(winner), AST_FLAG_EXCEPTION);
 			} else {
 				ast_clear_flag(ast_channel_flags(winner), AST_FLAG_EXCEPTION);
 			}
 			ast_channel_fdno_set(winner, fdmap[x].fdno);
+			ast_channel_unlock(winner);
 		} else {			/* this is an fd */
 			if (outfd) {
 				*outfd = pfds[x].fd;

-- 
To view, visit https://gerrit.asterisk.org/4930
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I2c5c8edec17c9bdad4a93291576838cb552ca5ed
Gerrit-PatchSet: 1
Gerrit-Project: asterisk
Gerrit-Branch: 13
Gerrit-Owner: Joshua Colp <jcolp at digium.com>