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[PULL,27/59] aio-win32: avoid out-of-bounds access to the events array

Message ID 1411137738-31280-28-git-send-email-stefanha@redhat.com
State New
Headers show

Commit Message

Stefan Hajnoczi Sept. 19, 2014, 2:41 p.m. UTC 
From: Paolo Bonzini <pbonzini@redhat.com>

If ret is WAIT_TIMEOUT and there was an event returned by select(),
we can write to a location after the end of the array.  But in
that case we can retry the WaitForMultipleObjects call with the
same set of events, so just move the event[ret - WAIT_OBJECT_0]
assignment inside the existin conditional.

Reported-by: TeLeMan <geleman@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: TeLeMan <geleman@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 aio-win32.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
diff mbox

Patch

diff --git a/aio-win32.c b/aio-win32.c
index 7daeae1..d81313b 100644
--- a/aio-win32.c
+++ b/aio-win32.c
@@ -335,6 +335,7 @@  bool aio_poll(AioContext *ctx, bool blocking)
         event = NULL;
         if ((DWORD) (ret - WAIT_OBJECT_0) < count) {
             event = events[ret - WAIT_OBJECT_0];
+            events[ret - WAIT_OBJECT_0] = events[--count];
         } else if (!have_select_revents) {
             break;
         }
@@ -343,9 +344,6 @@  bool aio_poll(AioContext *ctx, bool blocking)
         blocking = false;
 
         progress |= aio_dispatch_handlers(ctx, event);
-
-        /* Try again, but only call each handler once.  */
-        events[ret - WAIT_OBJECT_0] = events[--count];
     }
 
     progress |= timerlistgroup_run_timers(&ctx->tlg);