Patch "nfc: Fix the sockaddr length sanitization in llcp_sock_connect" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    nfc: Fix the sockaddr length sanitization in llcp_sock_connect

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfc-fix-the-sockaddr-length-sanitization-in-llcp_sock_connect.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 608c4adfcabab220142ee335a2a003ccd1c0b25b Mon Sep 17 00:00:00 2001
From: Mateusz Jurczyk <mjurczyk@google.com>
Date: Wed, 24 May 2017 12:26:20 +0200
Subject: nfc: Fix the sockaddr length sanitization in llcp_sock_connect

From: Mateusz Jurczyk <mjurczyk@google.com>

commit 608c4adfcabab220142ee335a2a003ccd1c0b25b upstream.

Fix the sockaddr length verification in the connect() handler of NFC/LLCP
sockets, to compare against the size of the actual structure expected on
input (sockaddr_nfc_llcp) instead of its shorter version (sockaddr_nfc).

Both structures are defined in include/uapi/linux/nfc.h. The fields
specific to the _llcp extended struct are as follows:

   276		__u8 dsap; /* Destination SAP, if known */
   277		__u8 ssap; /* Source SAP to be bound to */
   278		char service_name[NFC_LLCP_MAX_SERVICE_NAME]; /* Service name URI */;
   279		size_t service_name_len;

If the caller doesn't provide a sufficiently long sockaddr buffer, these
fields remain uninitialized (and they currently originate from the stack
frame of the top-level sys_connect handler). They are then copied by
llcp_sock_connect() into internal storage (nfc_llcp_sock structure), and
could be subsequently read back through the user-mode getsockname()
function (handled by llcp_sock_getname()). This would result in the
disclosure of up to ~70 uninitialized bytes from the kernel stack to
user-mode clients capable of creating AFC_NFC sockets.

Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/nfc/llcp_sock.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -655,8 +655,7 @@ static int llcp_sock_connect(struct sock
 
 	pr_debug("sock %p sk %p flags 0x%x\n", sock, sk, flags);
 
-	if (!addr || len < sizeof(struct sockaddr_nfc) ||
-	    addr->sa_family != AF_NFC)
+	if (!addr || len < sizeof(*addr) || addr->sa_family != AF_NFC)
 		return -EINVAL;
 
 	if (addr->service_name_len == 0 && addr->dsap == 0)


Patches currently in stable-queue which might be from mjurczyk@google.com are

queue-4.4/nfc-add-sockaddr-length-checks-before-accessing-sa_family-in-bind-handlers.patch
queue-4.4/nfc-ensure-presence-of-required-attributes-in-the-activate_target-handler.patch
queue-4.4/nfc-fix-the-sockaddr-length-sanitization-in-llcp_sock_connect.patch