This is a note to let you know that I've just added the patch titled
NFSD: Protect against send buffer overflow in NFSv2 READ
to the 5.15-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-protect-against-send-buffer-overflow-in-nfsv2-read.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 401bc1f90874280a80b93f23be33a0e7e2d1f912 Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Thu, 1 Sep 2022 15:10:18 -0400
Subject: NFSD: Protect against send buffer overflow in NFSv2 READ
From: Chuck Lever <chuck.lever@xxxxxxxxxx>
commit 401bc1f90874280a80b93f23be33a0e7e2d1f912 upstream.
Since before the git era, NFSD has conserved the number of pages
held by each nfsd thread by combining the RPC receive and send
buffers into a single array of pages. This works because there are
no cases where an operation needs a large RPC Call message and a
large RPC Reply at the same time.
Once an RPC Call has been received, svc_process() updates
svc_rqst::rq_res to describe the part of rq_pages that can be
used for constructing the Reply. This means that the send buffer
(rq_res) shrinks when the received RPC record containing the RPC
Call is large.
A client can force this shrinkage on TCP by sending a correctly-
formed RPC Call header contained in an RPC record that is
excessively large. The full maximum payload size cannot be
constructed in that case.
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfsd/nfsproc.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -182,6 +182,7 @@ nfsd_proc_read(struct svc_rqst *rqstp)
argp->count, argp->offset);
argp->count = min_t(u32, argp->count, NFSSVC_MAXBLKSIZE_V2);
+ argp->count = min_t(u32, argp->count, rqstp->rq_res.buflen);
v = 0;
len = argp->count;
Patches currently in stable-queue which might be from chuck.lever@xxxxxxxxxx are
queue-5.15/nfsd-protect-against-send-buffer-overflow-in-nfsv2-read.patch
queue-5.15/nfsd-protect-against-send-buffer-overflow-in-nfsv3-read.patch
queue-5.15/nfsd-protect-against-send-buffer-overflow-in-nfsv3-readdir.patch
