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 b5a52528f19ff6df5231294c28e4647f522bef2c..aca38ed1526e238b7695d737c02c43078eda449f 100644 (file)
--- 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);

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 71d735b125a0c19e84326b11f0af6ae20fb642dc..b207c76a873f3a86ca095c035505b4e07f82f61a 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1022,8 +1022,9 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
        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,