Due to change in client 8cfb9015280d ("NFS: Always provide aligned
buffers to the RPC read layers"), a read of 0xfff is aligned up to
server rsize of 0x0fff.
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.
This fixes the issue at server side by trimming reads past
NFS_OFFSET_MAX. It also adds a missing check for out of bound offset
in NFSv3.
Fixes: 8cfb9015280d ("NFS: Always provide aligned buffers to the RPC read layers")
Signed-off-by: Dan Aloni <dan.aloni@xxxxxxxxxxxx>
---
fs/nfsd/nfs4proc.c | 3 +++
fs/nfsd/vfs.c | 11 +++++++++++
2 files changed, 14 insertions(+)
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 486c5dba4b65..3b1e395a93b6 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -788,6 +788,9 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
trace_nfsd_read_start(rqstp, &cstate->current_fh,
read->rd_offset, read->rd_length);
+ if (unlikely(read->rd_offset + read->rd_length > NFS_OFFSET_MAX))
+ read->rd_length = NFS_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/vfs.c b/fs/nfsd/vfs.c
index 738d564ca4ce..4a209f807466 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1046,6 +1046,16 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
__be32 err;
trace_nfsd_read_start(rqstp, fhp, offset, *count);
+
+ if (unlikely(offset > NFS_OFFSET_MAX)) {
+ /* We can return this according to Section 3.3.6 */
+ err = nfserr_inval;
+ goto error;
+ }
+
+ if (unlikely(offset + *count > NFS_OFFSET_MAX))
+ *count = NFS_OFFSET_MAX - offset;
+
err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
if (err)
return err;
@@ -1058,6 +1068,7 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
nfsd_file_put(nf);
+error:
trace_nfsd_read_done(rqstp, fhp, offset, *count);
return err;
--
2.23.0
