kconfig: Avoid buffer underrun in choice input

svn path=/dists/sid/linux-2.6/; revision=17090

debian/changelog

@@ -1,3 +1,10 @@
+linux-2.6 (2.6.38-2) UNRELEASED; urgency=low
+
+  [ Ben Hutchings ]
+  * kconfig: Avoid buffer underrun in choice input (fixes FTBFS on mips)
+
+ -- Ben Hutchings <ben@decadent.org.uk>  Sat, 19 Mar 2011 05:17:42 +0000
+
 linux-2.6 (2.6.38-1) unstable; urgency=low
 
   * New upstream release: http://kernelnewbies.org/Linux_2_6_38

debian/patches/bugfix/all/kconfig-Avoid-buffer-underrun-in-choice-input.patch

@@ -0,0 +1,38 @@
+From f924897c3f04927d0d28d71b11c4019c9dd7a9f2 Mon Sep 17 00:00:00 2001
+From: Ben Hutchings <ben@decadent.org.uk>
+Date: Sat, 19 Mar 2011 04:11:33 +0000
+Subject: [PATCH] kconfig: Avoid buffer underrun in choice input
+
+commit 40aee729b350672c2550640622416a855e27938f ('kconfig: fix default
+value for choice input') fixed some cases where kconfig would select
+the wrong option from a choice with a single valid option and thus
+enter an infinite loop.
+
+However, this broke the test for user input of the form 'N?', because
+when kconfig selects the single valid option the input is zero-length
+and the test will read the byte before the input buffer.  If this
+happens to contain '?' (as it will in a mips build on Debian unstable
+today) then kconfig again enters an infinite loop.
+
+Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
+Cc: stable@kernel.org [2.6.17+]
+---
+ scripts/kconfig/conf.c |    2 +-
+ 1 files changed, 1 insertions(+), 1 deletions(-)
+
+diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
+index 659326c..006ad81 100644
+--- a/scripts/kconfig/conf.c
++++ b/scripts/kconfig/conf.c
+@@ -332,7 +332,7 @@ static int conf_choice(struct menu *menu)
+ 		}
+ 		if (!child)
+ 			continue;
+-		if (line[strlen(line) - 1] == '?') {
++		if (line[0] && line[strlen(line) - 1] == '?') {
+ 			print_help(child);
+ 			continue;
+ 		}
+-- 
+1.7.4.1
+

debian/patches/series/2

@@ -0,0 +1 @@
++ bugfix/all/kconfig-Avoid-buffer-underrun-in-choice-input.patch