Return-Path: linux-nfs-owner@vger.kernel.org Received: from mout.perfora.net ([74.208.4.195]:61292 "EHLO mout.perfora.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756676Ab3EQVdK (ORCPT ); Fri, 17 May 2013 17:33:10 -0400 From: Jim Rees To: Bruce Fields Cc: linux-nfs@vger.kernel.org Subject: [PATCH v2] nfsd: avoid undefined signed overflow Date: Fri, 17 May 2013 17:33:00 -0400 Message-Id: <1368826380-9864-1-git-send-email-rees@umich.edu> Sender: linux-nfs-owner@vger.kernel.org List-ID: In C, signed integer overflow results in undefined behavior, but unsigned overflow wraps around. So do the subtraction first, then cast to signed. Suggested-by: Joakim Tjernlund Signed-off-by: Jim Rees --- fs/nfsd/nfs4state.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 316ec84..9850329 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -3427,7 +3427,7 @@ grace_disallows_io(struct net *net, struct inode *inode) /* Returns true iff a is later than b: */ static bool stateid_generation_after(stateid_t *a, stateid_t *b) { - return (s32)a->si_generation - (s32)b->si_generation > 0; + return (s32)(a->si_generation - b->si_generation) > 0; } static __be32 check_stateid_generation(stateid_t *in, stateid_t *ref, bool has_session) -- 1.8.2.3