tree 858960b30b99c269b728075ea860bc8d77abfc81
parent 0cb4d23ae08c48f6bf3c29a8e5c4a74b8388b960
author Chuck Lever <chuck.lever@oracle.com> 1643652113 -0500
committer Chuck Lever <chuck.lever@oracle.com> 1644416568 -0500

NFSD: Fix ia_size underflow

iattr::ia_size is a loff_t, which is a signed 64-bit type. NFSv3 and
NFSv4 both define file size as an unsigned 64-bit type. Thus there
is a range of valid file size values an NFS client can send that is
already larger than Linux can handle.

Currently decode_fattr4() dumps a full u64 value into ia_size. If
that value happens to be larger than S64_MAX, then ia_size
underflows. I'm about to fix up the NFSv3 behavior as well, so let's
catch the underflow in the common code path: nfsd_setattr().

Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>