Patch "nfc: Fix the sockaddr length sanitization in llcp_sock_connect" has been added to the 4.9-stable tree

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 4.9-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-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mateusz Jurczyk <[email protected]>
Date: Wed, 24 May 2017 12:26:20 +0200
Subject: nfc: Fix the sockaddr length sanitization in llcp_sock_connect

From: Mateusz Jurczyk <[email protected]>

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.

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

@@ -661,8 +661,7 @@ 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 [email protected] are

queue-4.9/nfc-add-sockaddr-length-checks-before-accessing-sa_family-in-bind-handlers.patch queue-4.9/nfc-ensure-presence-of-required-attributes-in-the-activate_target-handler.patch queue-4.9/nfc-fix-the-sockaddr-length-sanitization-in-llcp_sock_connect.patch