[source] samba36: backport an upstream fix for an information leak (CVE-2017-15275)

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/aec1b6bfcbe1345eb10d8d104cb0d7dfc1f44423

commit aec1b6bfcbe1345eb10d8d104cb0d7dfc1f44423
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Mon Dec 4 09:56:32 2017 +0100

    samba36: backport an upstream fix for an information leak (CVE-2017-15275)
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 package/network/services/samba36/Makefile          |  2 +-
 .../samba36/patches/029-CVE-2017-15275.patch       | 40 ++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/package/network/services/samba36/Makefile b/package/network/services/samba36/Makefile
index 5564a78..42c23b4 100644
--- a/package/network/services/samba36/Makefile
+++ b/package/network/services/samba36/Makefile
@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=samba
 PKG_VERSION:=3.6.25
-PKG_RELEASE:=8
+PKG_RELEASE:=9
 
 PKG_SOURCE_URL:=https://download.samba.org/pub/samba \
 		https://download.samba.org/pub/samba/stable
diff --git a/package/network/services/samba36/patches/029-CVE-2017-15275.patch b/package/network/services/samba36/patches/029-CVE-2017-15275.patch
new file mode 100644
index 0000000..055a15e
--- /dev/null
+++ b/package/network/services/samba36/patches/029-CVE-2017-15275.patch
@@ -0,0 +1,40 @@
+From c1a22e59f87783d88dfbaeeb132b89be166b2754 Mon Sep 17 00:00:00 2001
+From: Jeremy Allison <jra at samba.org>
+Date: Wed, 20 Sep 2017 11:04:50 -0700
+Subject: [PATCH 2/2] s3: smbd: Chain code can return uninitialized memory when
+ talloc buffer is grown.
+
+Ensure we zero out unused grown area.
+
+CVE-2017-15275
+
+BUG: https://bugzilla.samba.org/show_bug.cgi?id=13077
+
+Signed-off-by: Jeremy Allison <jra at samba.org>
+---
+ source3/smbd/srvstr.c | 14 ++++++++++++++
+ 1 file changed, 14 insertions(+)
+
+--- a/source3/smbd/srvstr.c
++++ b/source3/smbd/srvstr.c
+@@ -70,6 +70,20 @@ ssize_t message_push_string(uint8 **outb
+ 		DEBUG(0, ("srvstr_push failed\n"));
+ 		return -1;
+ 	}
++
++	/*
++	 * Ensure we clear out the extra data we have
++	 * grown the buffer by, but not written to.
++	 */
++	if (buf_size + result < buf_size) {
++		return -1;
++	}
++	if (grow_size < result) {
++		return -1;
++	}
++
++	memset(tmp + buf_size + result, '\0', grow_size - result);
++
+ 	set_message_bcc((char *)tmp, smb_buflen(tmp) + result);
+ 
+ 	*outbuf = tmp;