From 7d08e1fae6150a3c0867dba6f75cf00946b3163c Mon Sep 17 00:00:00 2001 From: Petr Matousek <pmatouse@redhat.com> Date: Tue, 2 Jun 2015 14:32:06 +0200 Subject: [PATCH] i8254: fix out-of-bounds memory access in pit_ioport_read() Due converting PIO to the new memory read/write api we no longer provide separate I/O region lenghts for read and write operations. As a result, reading from PIT Mode/Command register will end with accessing pit->channels with invalid index. Fix this by ignoring read from the Mode/Command register. This is CVE-2015-3214. Signed-off-by: Petr Matousek <pmatouse@redhat.com> Reported-by: Matt Tait <matttait@google.com> --- hw/timer/i8254.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c index 3450c98..9b65a33 100644 --- a/hw/timer/i8254.c +++ b/hw/timer/i8254.c @@ -196,6 +196,12 @@ static uint64_t pit_ioport_read(void *opaque, hwaddr addr, PITChannelState *s; addr &= 3; + + if (addr == 3) { + /* Mode/Command register is write only, read is ignored */ + return 0; + } + s = &pit->channels[addr]; if (s->status_latched) { s->status_latched = 0; -- 2.1.0