Patch "nfsd: Limit end of page list when decoding NFSv4 WRITE" has been added to the 3.18-stable tree

[<gregkh@linuxfoundation.org>]

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

    nfsd: Limit end of page list when decoding NFSv4 WRITE

to the 3.18-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:
     nfsd-limit-end-of-page-list-when-decoding-nfsv4-write.patch
and it can be found in the queue-3.18 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 fc788f64f1f3eb31e87d4f53bcf1ab76590d5838 Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@oracle.com>
Date: Fri, 18 Aug 2017 11:12:19 -0400
Subject: nfsd: Limit end of page list when decoding NFSv4 WRITE

From: Chuck Lever <chuck.lever@oracle.com>

commit fc788f64f1f3eb31e87d4f53bcf1ab76590d5838 upstream.

When processing an NFSv4 WRITE operation, argp->end should never
point past the end of the data in the final page of the page list.
Otherwise, nfsd4_decode_compound can walk into uninitialized memory.

More critical, nfsd4_decode_write is failing to increment argp->pagelen
when it increments argp->pagelist.  This can cause later xdr decoders
to assume more data is available than really is, which can cause server
crashes on malformed requests.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfsd/nfs4xdr.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -127,7 +127,7 @@ static void next_decode_page(struct nfsd
 	argp->p = page_address(argp->pagelist[0]);
 	argp->pagelist++;
 	if (argp->pagelen < PAGE_SIZE) {
-		argp->end = argp->p + (argp->pagelen>>2);
+		argp->end = argp->p + XDR_QUADLEN(argp->pagelen);
 		argp->pagelen = 0;
 	} else {
 		argp->end = argp->p + (PAGE_SIZE>>2);
@@ -1235,9 +1235,7 @@ nfsd4_decode_write(struct nfsd4_compound
 		argp->pagelen -= pages * PAGE_SIZE;
 		len -= pages * PAGE_SIZE;
 
-		argp->p = (__be32 *)page_address(argp->pagelist[0]);
-		argp->pagelist++;
-		argp->end = argp->p + XDR_QUADLEN(PAGE_SIZE);
+		next_decode_page(argp);
 	}
 	argp->p += XDR_QUADLEN(len);
 


Patches currently in stable-queue which might be from chuck.lever@oracle.com are

queue-3.18/nfsd-limit-end-of-page-list-when-decoding-nfsv4-write.patch