From d4862a87e31a51de9eb260f25c9e99a75efe3235 Mon Sep 17 00:00:00 2001 From: Petr Matousek Date: Wed, 17 Jun 2015 12:46:11 +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. Reported-by: Matt Tait Fixes: 0505bcdec8228d8de39ab1a02644e71999e7c052 Cc: qemu-stable@nongnu.org Signed-off-by: Petr Matousek Signed-off-by: Paolo Bonzini --- hw/timer/i8254.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c index 3450c98637..9b65a33692 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; -- GitLab