From: Jim Rees <rees@umich.edu>
Date: Fri, 17 May 2013 21:33:00 +0000 (-0400)
Subject: nfsd: avoid undefined signed overflow
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=1a9357f443d64aa41e9b0dc414953663a6fcca19;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

nfsd: avoid undefined signed overflow

In C, signed integer overflow results in undefined behavior, but unsigned
overflow wraps around. So do the subtraction first, then cast to signed.

Reported-by: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 91ead0ed9f11..72f0c4e9a942 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)