From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49101) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bzN9W-0001ne-4c for qemu-devel@nongnu.org; Wed, 26 Oct 2016 08:17:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bzN9S-0002FR-6g for qemu-devel@nongnu.org; Wed, 26 Oct 2016 08:17:54 -0400 From: P J P Date: Wed, 26 Oct 2016 17:47:33 +0530 Message-Id: <1477484253-32731-1-git-send-email-ppandit@redhat.com> Subject: [Qemu-devel] [PATCH v2] net: smc91c111: check packet number and data register index List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu Developers Cc: qemu-arm , Jason Wang , Azure Yang , Peter Maydell , Prasad J Pandit From: Prasad J Pandit SMSC91C111 Ethernet interface emulator has registers to store 'packet number' and a 'pointer' to Tx/Rx FIFO buffer area. These two are used to derive an address to access into 'data' registers. If they are set incorrectly, they could lead to an OOB r/w access beyond packet 'data' area. Add check to avoid it. Reported-by: Azure Yang Signed-off-by: Prasad J Pandit --- hw/net/smc91c111.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) Update per: -> https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg06108.html diff --git a/hw/net/smc91c111.c b/hw/net/smc91c111.c index 3b16dcf..f9698ca 100644 --- a/hw/net/smc91c111.c +++ b/hw/net/smc91c111.c @@ -418,7 +418,7 @@ static void smc91c111_writeb(void *opaque, hwaddr offset, /* Ignore. */ return; case 2: /* Packet Number Register */ - s->packet_num = value; + s->packet_num = value & 0x03F; return; case 3: case 4: case 5: /* Should be readonly, but linux writes to them anyway. Ignore. */ @@ -438,13 +438,16 @@ static void smc91c111_writeb(void *opaque, hwaddr offset, n = s->rx_fifo[0]; else n = s->packet_num; - p = s->ptr & 0x07ff; + p = s->ptr; if (s->ptr & 0x4000) { s->ptr = (s->ptr & 0xf800) | ((s->ptr + 1) & 0x7ff); } else { p += (offset & 3); } - s->data[n][p] = value; + p &= 0x07ff; + if (n < NUM_PACKETS && n & s->allocated) { + s->data[n][p] = value; + } } return; case 12: /* Interrupt ACK. */ @@ -584,13 +587,17 @@ static uint32_t smc91c111_readb(void *opaque, hwaddr offset) n = s->rx_fifo[0]; else n = s->packet_num; - p = s->ptr & 0x07ff; + p = s->ptr; if (s->ptr & 0x4000) { s->ptr = (s->ptr & 0xf800) | ((s->ptr + 1) & 0x07ff); } else { p += (offset & 3); } - return s->data[n][p]; + p &= 0x07ff; + if (n < NUM_PACKETS && n & s->allocated) { + return s->data[n][p]; + } + return 0; } case 12: /* Interrupt status. */ return s->int_level; -- 2.7.4