xen: off by one errors in multicalls.c

b->args[] has MC_ARGS elements, so the comparison here should be
">=" instead of ">".  Otherwise we read past the end of the array
one space.

CC: stable@kernel.org
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
index 8bff7e7c290b..1b2b73ff0a6e 100644
--- a/arch/x86/xen/multicalls.c
+++ b/arch/x86/xen/multicalls.c
@@ -189,10 +189,10 @@ struct multicall_space __xen_mc_entry(size_t args)
         unsigned argidx = roundup(b->argidx, sizeof(u64));
 
         BUG_ON(preemptible());
-        BUG_ON(b->argidx > MC_ARGS);
+        BUG_ON(b->argidx >= MC_ARGS);
 
         if (b->mcidx == MC_BATCH ||
-            (argidx + args) > MC_ARGS) {
+            (argidx + args) >= MC_ARGS) {
                 mc_stats_flush(b->mcidx == MC_BATCH ? FL_SLOTS : FL_ARGS);
                 xen_mc_flush();
                 argidx = roundup(b->argidx, sizeof(u64));
@@ -206,7 +206,7 @@ struct multicall_space __xen_mc_entry(size_t args)
         ret.args = &b->args[argidx];
         b->argidx = argidx + args;
 
-        BUG_ON(b->argidx > MC_ARGS);
+        BUG_ON(b->argidx >= MC_ARGS);
         return ret;
 }
 
@@ -216,7 +216,7 @@ struct multicall_space xen_mc_extend_args(unsigned long op, size_t size)
         struct multicall_space ret = { NULL, NULL };
 
         BUG_ON(preemptible());
-        BUG_ON(b->argidx > MC_ARGS);
+        BUG_ON(b->argidx >= MC_ARGS);
 
         if (b->mcidx == 0)
                 return ret;
@@ -224,14 +224,14 @@ struct multicall_space xen_mc_extend_args(unsigned long op, size_t size)
         if (b->entries[b->mcidx - 1].op != op)
                 return ret;
 
-        if ((b->argidx + size) > MC_ARGS)
+        if ((b->argidx + size) >= MC_ARGS)
                 return ret;
 
         ret.mc = &b->entries[b->mcidx - 1];
         ret.args = &b->args[b->argidx];
         b->argidx += size;
 
-        BUG_ON(b->argidx > MC_ARGS);
+        BUG_ON(b->argidx >= MC_ARGS);
         return ret;
 }