NFSD: Clamp WRITE offsets
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>
diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index b5a5252..aca38ed 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -203,6 +203,11 @@ 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, &argp->payload);