This is a note to let you know that I've just added the patch titled
NFSD: Fix the behavior of READ near OFFSET_MAX
to the 5.10-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-fix-the-behavior-of-read-near-offset_max.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d4fd9408fd45502d3b7256922faee3f9c7917855
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Fri Feb 4 15:19:34 2022 -0500
NFSD: Fix the behavior of READ near OFFSET_MAX
[ Upstream commit 0cb4d23ae08c48f6bf3c29a8e5c4a74b8388b960 ]
Dan Aloni reports:
> Due to commit 8cfb9015280d ("NFS: Always provide aligned buffers to
> the RPC read layers") on the client, a read of 0xfff is aligned up
> to server rsize of 0x1000.
>
> As a result, in a test where the server has a file of size
> 0x7fffffffffffffff, and the client tries to read from the offset
> 0x7ffffffffffff000, the read causes loff_t overflow in the server
> and it returns an NFS code of EINVAL to the client. The client as
> a result indefinitely retries the request.
The Linux NFS client does not handle NFS?ERR_INVAL, even though all
NFS specifications permit servers to return that status code for a
READ.
Instead of NFS?ERR_INVAL, have out-of-range READ requests succeed
and return a short result. Set the EOF flag in the result to prevent
the client from retrying the READ request. This behavior appears to
be consistent with Solaris NFS servers.
Note that NFSv3 and NFSv4 use u64 offset values on the wire. These
must be converted to loff_t internally before use -- an implicit
type cast is not adequate for this purpose. Otherwise VFS checks
against sb->s_maxbytes do not work properly.
Reported-by: Dan Aloni <dan.aloni@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 1515c32e08db2..b540489ea240d 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -150,13 +150,17 @@ nfsd3_proc_read(struct svc_rqst *rqstp)
unsigned int len;
int v;
- argp->count = min_t(u32, argp->count, max_blocksize);
-
dprintk("nfsd: READ(3) %s %lu bytes at %Lu\n",
SVCFH_fmt(&argp->fh),
(unsigned long) argp->count,
(unsigned long long) argp->offset);
+ argp->count = min_t(u32, argp->count, max_blocksize);
+ if (argp->offset > (u64)OFFSET_MAX)
+ argp->offset = (u64)OFFSET_MAX;
+ if (argp->offset + argp->count > (u64)OFFSET_MAX)
+ argp->count = (u64)OFFSET_MAX - argp->offset;
+
v = 0;
len = argp->count;
resp->pages = rqstp->rq_next_page;
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 451190813302e..f3d6bd2bfa4f7 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -782,12 +782,16 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
__be32 status;
read->rd_nf = NULL;
- if (read->rd_offset >= OFFSET_MAX)
- return nfserr_inval;
trace_nfsd_read_start(rqstp, &cstate->current_fh,
read->rd_offset, read->rd_length);
+ read->rd_length = min_t(u32, read->rd_length, svc_max_payload(rqstp));
+ if (read->rd_offset > (u64)OFFSET_MAX)
+ read->rd_offset = (u64)OFFSET_MAX;
+ if (read->rd_offset + read->rd_length > (u64)OFFSET_MAX)
+ read->rd_length = (u64)OFFSET_MAX - read->rd_offset;
+
/*
* If we do a zero copy read, then a client will see read data
* that reflects the state of the file *after* performing the
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index adf97d72bda80..be0995bb9459a 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3997,10 +3997,8 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
}
xdr_commit_encode(xdr);
- maxcount = svc_max_payload(resp->rqstp);
- maxcount = min_t(unsigned long, maxcount,
+ maxcount = min_t(unsigned long, read->rd_length,
(xdr->buf->buflen - xdr->buf->len));
- maxcount = min_t(unsigned long, maxcount, read->rd_length);
if (file->f_op->splice_read &&
test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags))
@@ -4834,10 +4832,8 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
return nfserr_resource;
xdr_commit_encode(xdr);
- maxcount = svc_max_payload(resp->rqstp);
- maxcount = min_t(unsigned long, maxcount,
+ maxcount = min_t(unsigned long, read->rd_length,
(xdr->buf->buflen - xdr->buf->len));
- maxcount = min_t(unsigned long, maxcount, read->rd_length);
count = maxcount;
eof = read->rd_offset >= i_size_read(file_inode(file));
