This is a note to let you know that I've just added the patch titled
NFSD: Protect against send buffer overflow in NFSv3 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-nfsv3-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 fa6be9cc6e80ec79892ddf08a8c10cabab9baf38 Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Thu, 1 Sep 2022 15:10:24 -0400
Subject: NFSD: Protect against send buffer overflow in NFSv3 READ
From: Chuck Lever <chuck.lever@xxxxxxxxxx>
commit fa6be9cc6e80ec79892ddf08a8c10cabab9baf38 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/nfs3proc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -146,7 +146,6 @@ nfsd3_proc_read(struct svc_rqst *rqstp)
{
struct nfsd3_readargs *argp = rqstp->rq_argp;
struct nfsd3_readres *resp = rqstp->rq_resp;
- u32 max_blocksize = svc_max_payload(rqstp);
unsigned int len;
int v;
@@ -155,7 +154,8 @@ nfsd3_proc_read(struct svc_rqst *rqstp)
(unsigned long) argp->count,
(unsigned long long) argp->offset);
- argp->count = min_t(u32, argp->count, max_blocksize);
+ argp->count = min_t(u32, argp->count, svc_max_payload(rqstp));
+ argp->count = min_t(u32, argp->count, rqstp->rq_res.buflen);
if (argp->offset > (u64)OFFSET_MAX)
argp->offset = (u64)OFFSET_MAX;
if (argp->offset + argp->count > (u64)OFFSET_MAX)
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
