2 files changed, 57 insertions, 0 deletions

diff --git a/meta-networking/recipes-netkit/netkit-telnet/files/0001-telnetd-utility.c-Fix-buffer-overflow-in-netoprintf.patch b/meta-networking/recipes-netkit/netkit-telnet/files/0001-telnetd-utility.c-Fix-buffer-overflow-in-netoprintf.patch
new file mode 100644
index 0000000000..8f983e40ab
--- /dev/null
+++ b/meta-networking/recipes-netkit/netkit-telnet/files/0001-telnetd-utility.c-Fix-buffer-overflow-in-netoprintf.patch
@@ -0,0 +1,56 @@
+From 9c81c8e5bc7782e8ae12c078615abc3c896059f2 Mon Sep 17 00:00:00 2001
+From: Julius Hemanth Pitti <jpitti@cisco.com>
+Date: Tue, 14 Jul 2020 22:34:19 -0700
+Subject: [PATCH] telnetd/utility.c: Fix buffer overflow in netoprintf
+
+As per man page of vsnprintf, when formated
+string size is greater than "size"(2nd argument),
+then vsnprintf returns size of formated string,
+not "size"(2nd argument).
+
+netoprintf() was not handling a case where
+return value of vsnprintf is greater than
+"size"(2nd argument), results in buffer overflow
+while adjusting "nfrontp" pointer to point
+beyond "netobuf" buffer.
+
+Here is one such case where "nfrontp"
+crossed boundaries of "netobuf", and
+pointing to another global variable.
+
+(gdb) p &netobuf[8255]
+$5 = 0x55c93afe8b1f <netobuf+8255> ""
+(gdb) p nfrontp
+$6 = 0x55c93afe8c20 <terminaltype> "\377"
+(gdb) p &terminaltype
+$7 = (char **) 0x55c93afe8c20 <terminaltype>
+(gdb)
+
+This resulted in crash of telnetd service
+with segmentation fault.
+
+Though this is DoS security bug, I couldn't
+find any CVE ID for this.
+
+Upstream-Status: Pending
+
+Signed-off-by: Julius Hemanth Pitti <jpitti@cisco.com>
+---
+ telnetd/utility.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/telnetd/utility.c b/telnetd/utility.c
+index b9a46a6..4811f14 100644
+--- a/telnetd/utility.c
++++ b/telnetd/utility.c
+@@ -66,7 +66,7 @@ netoprintf(const char *fmt, ...)
+       len = vsnprintf(nfrontp, maxsize, fmt, ap);
+       va_end(ap);
+ 
+-      if (len<0 || len==maxsize) {
++      if (len<0 || len>=maxsize) {
+         /* didn't fit */
+         netflush();
+       }
+--
+2.19.1
diff --git a/meta-networking/recipes-netkit/netkit-telnet/netkit-telnet_0.17.bb b/meta-networking/recipes-netkit/netkit-telnet/netkit-telnet_0.17.bb
index 0e92add633..08dd532b62 100644
--- a/meta-networking/recipes-netkit/netkit-telnet/netkit-telnet_0.17.bb
+++ b/meta-networking/recipes-netkit/netkit-telnet/netkit-telnet_0.17.bb
@@ -13,6 +13,7 @@ SRC_URI = "http://ftp.linux.org.uk/pub/linux/Networking/netkit/${BP}.tar.gz \
            file://0001-telnet-telnetd-Fix-print-format-strings.patch \
            file://0001-telnet-telnetd-Fix-deadlock-on-cleanup.patch \
            file://CVE-2020-10188.patch \
+           file://0001-telnetd-utility.c-Fix-buffer-overflow-in-netoprintf.patch \
            "
 
 UPSTREAM_CHECK_URI = "${DEBIAN_MIRROR}/main/n/netkit-telnet/"