From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Thu, 13 Oct 2016 14:17:06 +0000 (+0200)
Subject: telnetd: ifdef out a buggy error handling code path
X-Git-Tag: 1_26_0~150
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=662634b82902afa84a8c978c259fa0bbd7bc8c09;p=oweals%2Fbusybox.git

telnetd: ifdef out a buggy error handling code path

Here, not handling the error is would just eat one input 0xff char.
Correct handling would need even more corner case handling,
as-is buggy handling corrupts the buffer.
Since we just been told by kernel that pty is ready,
EAGAIN should not be happening here anyway.

function                                             old     new   delta
telnetd_main                                        1798    1785     -13

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---

diff --git a/networking/telnetd.c b/networking/telnetd.c
index 1de3abcc7..303ef1be7 100644
--- a/networking/telnetd.c
+++ b/networking/telnetd.c
@@ -192,8 +192,16 @@ safe_write_to_pty_decode_iac(struct tsession *ts)
 		/* Literal 255 (emacs M-DEL) */
 		//bb_error_msg("255!");
 		rc = safe_write(ts->ptyfd, &buf[1], 1);
+		/*
+		 * If we went through buffered_IAC_for_pty==1 path,
+		 * bailing out on error like below messes up the buffer.
+		 * EAGAIN is highly unlikely here, other errors will be
+		 * repeated on next write, let's just skip error check.
+		 */
+#if 0
 		if (rc <= 0)
 			return rc;
+#endif
 		rc = 2;
 		goto update_and_return;
 	}