4.6p1 chan_read_failed error

[Darren Tucker]

On Fri, Mar 23, 2007 at 03:54:46PM -0700, Jim Stosick wrote:
> The 4.6p1 sshd is logging this error during remote commands or file 
> transfers:
> 
>    error: channel 0: chan_read_failed for istate 3
> 
> Platform is Solaris 8, 4.6p1 + OpenSSL 0.9.8d.
> 
> The commands and transfers work correctly, so the error message appears 
> to be spurious.  The error message does not appear when processing logins.
> 
> Otherwise 4.6p1 is running without any apparent problems.  This error 
> did not occur running 4.5p1.
[...]

I suspect this is related to the change for bug #52.  You could try
reverting the following patch ("patch -p1 -R") and see if the error
messages stop.

Index: openssh/channels.c
diff -u openssh/channels.c:1.250 openssh/channels.c:1.251
--- openssh/channels.c:1.250	Fri Jan  5 16:30:16 2007
+++ openssh/channels.c	Mon Jan 29 10:16:28 2007
@@ -1449,10 +1449,11 @@
 	int len;
 
 	if (c->rfd != -1 &&
-	    FD_ISSET(c->rfd, readset)) {
+	    (c->detach_close || FD_ISSET(c->rfd, readset))) {
 		errno = 0;
 		len = read(c->rfd, buf, sizeof(buf));
-		if (len < 0 && (errno == EINTR || errno == EAGAIN))
+		if (len < 0 && (errno == EINTR ||
+		    (errno == EAGAIN && !(c->isatty && c->detach_close))))
 			return 1;
 #ifndef PTY_ZEROREAD
 		if (len <= 0) {
@@ -1604,11 +1605,12 @@
 				c->local_consumed += len;
 			}
 		} else if (c->extended_usage == CHAN_EXTENDED_READ &&
-		    FD_ISSET(c->efd, readset)) {
+		    (c->detach_close || FD_ISSET(c->efd, readset))) {
 			len = read(c->efd, buf, sizeof(buf));
 			debug2("channel %d: read %d from efd %d",
 			    c->self, len, c->efd);
-			if (len < 0 && (errno == EINTR || errno == EAGAIN))
+			if (len < 0 && (errno == EINTR ||
+			    (errno == EAGAIN && !c->detach_close)))
 				return 1;
 			if (len <= 0) {
 				debug2("channel %d: closing read-efd %d",
Index: openssh/serverloop.c
diff -u openssh/serverloop.c:1.150 openssh/serverloop.c:1.151
--- openssh/serverloop.c:1.150	Tue Oct 24 03:02:41 2006
+++ openssh/serverloop.c	Mon Jan 29 10:16:28 2007
@@ -280,6 +280,7 @@
 	struct timeval tv, *tvp;
 	int ret;
 	int client_alive_scheduled = 0;
+	int program_alive_scheduled = 0;
 
 	/*
 	 * if using client_alive, set the max timeout accordingly,
@@ -317,6 +318,7 @@
 		 * the client, try to get some more data from the program.
 		 */
 		if (packet_not_very_much_data_to_write()) {
+			program_alive_scheduled = child_terminated;
 			if (!fdout_eof)
 				FD_SET(fdout, *readsetp);
 			if (!fderr_eof)
@@ -362,8 +364,16 @@
 		memset(*writesetp, 0, *nallocp);
 		if (errno != EINTR)
 			error("select: %.100s", strerror(errno));
-	} else if (ret == 0 && client_alive_scheduled)
-		client_alive_check();
+	} else {
+		if (ret == 0 && client_alive_scheduled)
+			client_alive_check();
+		if (!compat20 && program_alive_scheduled && fdin_is_tty) {
+			if (!fdout_eof)
+				FD_SET(fdout, *readsetp);
+			if (!fderr_eof)
+				FD_SET(fderr, *readsetp);
+		}
+	}
 
 	notify_done(*readsetp);
 }
@@ -407,7 +417,8 @@
 	if (!fdout_eof && FD_ISSET(fdout, readset)) {
 		errno = 0;
 		len = read(fdout, buf, sizeof(buf));
-		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
+		if (len < 0 && (errno == EINTR ||
+		    (errno == EAGAIN && !child_terminated))) {
 			/* do nothing */
 #ifndef PTY_ZEROREAD
 		} else if (len <= 0) {
@@ -425,7 +436,8 @@
 	if (!fderr_eof && FD_ISSET(fderr, readset)) {
 		errno = 0;
 		len = read(fderr, buf, sizeof(buf));
-		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
+		if (len < 0 && (errno == EINTR ||
+		    (errno == EAGAIN && !child_terminated))) {
 			/* do nothing */
 #ifndef PTY_ZEROREAD
 		} else if (len <= 0) {

-- 
Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.