Patch "afs: Deal with an empty callback array" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    afs: Deal with an empty callback array

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:
     afs-deal-with-an-empty-callback-array.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 <stable@vger.kernel.org> know about it.


>From foo@baz Mon Dec 18 14:12:34 CET 2017
From: Marc Dionne <marc.dionne@auristor.com>
Date: Thu, 16 Mar 2017 16:27:44 +0000
Subject: afs: Deal with an empty callback array

From: Marc Dionne <marc.dionne@auristor.com>


[ Upstream commit bcd89270d93b7edebb5de5e5e7dca1a77a33496e ]

Servers may send a callback array that is the same size as
the FID array, or an empty array.  If the callback count is
0, the code would attempt to read (fid_count * 12) bytes of
data, which would fail and result in an unmarshalling error.
This would lead to stale data for remotely modified files
or directories.

Store the callback array size in the internal afs_call
structure and use that to determine the amount of data to
read.

Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/afs/cmservice.c |   11 +++++------
 fs/afs/internal.h  |    5 ++++-
 2 files changed, 9 insertions(+), 7 deletions(-)

--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -168,7 +168,6 @@ static int afs_deliver_cb_callback(struc
 	struct afs_callback *cb;
 	struct afs_server *server;
 	__be32 *bp;
-	u32 tmp;
 	int ret, loop;
 
 	_enter("{%u}", call->unmarshall);
@@ -230,9 +229,9 @@ static int afs_deliver_cb_callback(struc
 		if (ret < 0)
 			return ret;
 
-		tmp = ntohl(call->tmp);
-		_debug("CB count: %u", tmp);
-		if (tmp != call->count && tmp != 0)
+		call->count2 = ntohl(call->tmp);
+		_debug("CB count: %u", call->count2);
+		if (call->count2 != call->count && call->count2 != 0)
 			return -EBADMSG;
 		call->offset = 0;
 		call->unmarshall++;
@@ -240,14 +239,14 @@ static int afs_deliver_cb_callback(struc
 	case 4:
 		_debug("extract CB array");
 		ret = afs_extract_data(call, call->buffer,
-				       call->count * 3 * 4, false);
+				       call->count2 * 3 * 4, false);
 		if (ret < 0)
 			return ret;
 
 		_debug("unmarshall CB array");
 		cb = call->request;
 		bp = call->buffer;
-		for (loop = call->count; loop > 0; loop--, cb++) {
+		for (loop = call->count2; loop > 0; loop--, cb++) {
 			cb->version	= ntohl(*bp++);
 			cb->expiry	= ntohl(*bp++);
 			cb->type	= ntohl(*bp++);
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -105,7 +105,10 @@ struct afs_call {
 	unsigned		request_size;	/* size of request data */
 	unsigned		reply_max;	/* maximum size of reply */
 	unsigned		first_offset;	/* offset into mapping[first] */
-	unsigned		last_to;	/* amount of mapping[last] */
+	union {
+		unsigned	last_to;	/* amount of mapping[last] */
+		unsigned	count2;		/* count used in unmarshalling */
+	};
 	unsigned char		unmarshall;	/* unmarshalling phase */
 	bool			incoming;	/* T if incoming call */
 	bool			send_pages;	/* T if data from mapping should be sent */


Patches currently in stable-queue which might be from marc.dionne@auristor.com are

queue-4.9/afs-populate-group-id-from-vnode-status.patch
queue-4.9/afs-adjust-mode-bits-processing.patch
queue-4.9/afs-populate-and-use-client-modification-time.patch
queue-4.9/afs-deal-with-an-empty-callback-array.patch