[PATCH 5.10 010/116] NFSD: Clamp WRITE offsets

Greg Kroah-Hartman
2022-02-14T09:50:15Z

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

commit 6260d9a56ab352b54891ec66ab0eced57d55abc6 upstream.

Ensure that a client cannot specify a WRITE range that falls in a
byte range outside what the kernel's internal types (such as loff_t,
which is signed) can represent. The kiocb iterators, invoked in
nfsd_vfs_write(), should properly limit write operations to within
the underlying file system's s_maxbytes.

Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfsd/nfs3proc.c | 5 +++++
fs/nfsd/nfs4proc.c | 5 +++--
2 files changed, 8 insertions(+), 2 deletions(-)

--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -183,6 +183,11 @@ nfsd3_proc_write(struct svc_rqst *rqstp)
(unsigned long long) argp->offset,
argp->stable? " stable" : "");

+ resp->status = nfserr_fbig;
+ if (argp->offset > (u64)OFFSET_MAX ||
+ argp->offset + argp->len > (u64)OFFSET_MAX)
+ return rpc_success;
+
fh_copy(&resp->fh, &argp->fh);
resp->committed = argp->stable;
nvecs = svc_fill_write_vector(rqstp, rqstp->rq_arg.pages,
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1008,8 +1008,9 @@ nfsd4_write(struct svc_rqst *rqstp, stru
unsigned long cnt;
int nvecs;

- if (write->wr_offset >= OFFSET_MAX)
- return nfserr_inval;
+ if (write->wr_offset > (u64)OFFSET_MAX ||
+ write->wr_offset + write->wr_buflen > (u64)OFFSET_MAX)
+ return nfserr_fbig;

cnt = write->wr_buflen;
trace_nfsd_write_start(rqstp, &cstate->current_fh,