[COMMITTED 2.25 6/8] glob: Fix buffer overflow during GLOB_TILDE unescaping [BZ #22332]

[Aurelien Jarno]

From: Paul Eggert <eggert@cs.ucla.edu>

(cherry picked from commit a159b53fa059947cc2548e3b0d5bdcf7b9630ba8)
---
 ChangeLog    | 6 ++++++
 NEWS         | 4 ++++
 posix/glob.c | 4 ++--
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c19862d829..951fe6f882 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-10-22  Paul Eggert <eggert@cs.ucla.edu>
+
+	[BZ #22332]
+	* posix/glob.c (__glob): Fix buffer overflow during GLOB_TILDE
+	unescaping.
+
 2017-10-21  Florian Weimer  <fweimer@redhat.com>
 
 	* posix/Makefile (tests): Add tst-glob-tilde.
diff --git a/NEWS b/NEWS
index c353ce6273..40ecd30fc5 100644
--- a/NEWS
+++ b/NEWS
@@ -17,6 +17,10 @@ Security related changes:
   processing, leading to a memory leak and, potentially, to a denial
   of service.
 
+  The glob function, when invoked with GLOB_TILDE and without
+  GLOB_NOESCAPE, could write past the end of a buffer while
+  unescaping user names.  Reported by Tim Rühsen.
+
 The following bugs are resolved with this release:
 
   [20257] sunrpc: clntudp_call does not enforce timeout when receiving data
diff --git a/posix/glob.c b/posix/glob.c
index c761c0861d..b2273ea7bc 100644
--- a/posix/glob.c
+++ b/posix/glob.c
@@ -850,11 +850,11 @@ glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		  char *p = mempcpy (newp, dirname + 1,
 				     unescape - dirname - 1);
 		  char *q = unescape;
-		  while (*q != '\0')
+		  while (q != end_name)
 		    {
 		      if (*q == '\\')
 			{
-			  if (q[1] == '\0')
+			  if (q + 1 == end_name)
 			    {
 			      /* "~fo\\o\\" unescape to user_name "foo\\",
 				 but "~fo\\o\\/" unescape to user_name
-- 
2.15.0