[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2] xenfb.c: avoid expensive loops when prod <= out_cons
If the frontend sets out_cons to a value higher than out_prod, it will cause xenfb_handle_events to loop about 2^32 times. Avoid that by using better checks at the beginning of the function. Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> Reported-by: Ling Liu <liuling-it@xxxxxx> --- diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c index 4e2a27a..594baff 100644 --- a/hw/display/xenfb.c +++ b/hw/display/xenfb.c @@ -789,8 +789,9 @@ static void xenfb_handle_events(struct XenFB *xenfb) prod = page->out_prod; out_cons = page->out_cons; - if (prod == out_cons) - return; + if (prod - out_cons >= XENFB_OUT_RING_LEL) { + return; + } xen_rmb(); /* ensure we see ring contents up to prod */ for (cons = out_cons; cons != prod; cons++) { union xenfb_out_event *event = &XENFB_OUT_RING_REF(page, cons); _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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