[Xen-devel] [PATCH 6/8] tools/xenalyze: Fix off-by-one in MAX_CPUS range checks

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

Skip action / throw error if cpu/vcpu >= MAX_CPUS  rather than >.

Also add an assertion to vcpu_find, to make future errors of this kind
not out-of-bounds.

CID 1306871
CID 1306870
CID 1306869
CID 1306867

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
---
CC: Ian Jackson <ian.jackson@xxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/xentrace/xenalyze.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/tools/xentrace/xenalyze.c b/tools/xentrace/xenalyze.c
index 249bebd..3e26a4c 100644
--- a/tools/xentrace/xenalyze.c
+++ b/tools/xentrace/xenalyze.c
@@ -6860,6 +6860,13 @@ struct vcpu_data * vcpu_find(int did, int vid)
     struct domain_data *d;
     struct vcpu_data *v;
 
+    /* "Graceful" handling of vid >= MAX_CPUS should be handled elsewhere */
+    if ( vid >= MAX_CPUS ) {
+        fprintf(stderr, "%s: vcpu %d exceeds MAX_CPUS %d!\n",
+                __func__, vid, MAX_CPUS);
+        error(ERR_ASSERT, NULL);
+    }
+
     d = domain_find(did);
 
     v = d->vcpu[vid];
@@ -7131,7 +7138,7 @@ void sched_runstate_process(struct pcpu_info *p)
         }
     }
 
-    if(r->vcpu > MAX_CPUS)
+    if(r->vcpu >= MAX_CPUS)
     {
         fprintf(warn, "%s: vcpu %u > MAX_VCPUS %d!\n",
                 __func__, r->vcpu, MAX_CPUS);
@@ -7441,14 +7448,14 @@ void sched_switch_process(struct pcpu_info *p)
                r->prev_dom, r->prev_vcpu,
                r->next_dom, r->next_vcpu);
 
-    if(r->prev_vcpu > MAX_CPUS)
+    if(r->prev_vcpu >= MAX_CPUS)
     {
         fprintf(warn, "%s: prev_vcpu %u > MAX_VCPUS %d!\n",
                 __func__, r->prev_vcpu, MAX_CPUS);
         return;
     }
 
-    if(r->next_vcpu > MAX_CPUS)
+    if(r->next_vcpu >= MAX_CPUS)
     {
         fprintf(warn, "%s: next_vcpu %u > MAX_VCPUS %d!\n",
                 __func__, r->next_vcpu, MAX_CPUS);
@@ -8518,7 +8525,7 @@ off_t scan_for_new_pcpu(off_t offset) {
 
     cd = (typeof(cd))rec.u.notsc.data;
 
-    if ( cd->cpu > MAX_CPUS )
+    if ( cd->cpu >= MAX_CPUS )
     {
         fprintf(stderr, "%s: cpu %d exceeds MAX_CPU %d!\n",
                 __func__, cd->cpu, MAX_CPUS);
@@ -8738,7 +8745,7 @@ void process_cpu_change(struct pcpu_info *p) {
                 (unsigned long long)p->file_offset);
     }
 
-    if(r->cpu > MAX_CPUS)
+    if(r->cpu >= MAX_CPUS)
     {
         fprintf(stderr, "FATAL: cpu %d > MAX_CPUS %d.\n",
                 r->cpu, MAX_CPUS);
-- 
2.1.4


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