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From 03f2b3e5198471d80c3740450113643dff2109ce Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Thu, 16 Jul 2015 16:15:58 +0200
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Subject: [PATCH 1/3] ide: Check array bounds before writing to io_buffer
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(CVE-2015-5154)
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Message-id: <1437056160-3284-2-git-send-email-kwolf@redhat.com>
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Patchwork-id: n/a
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O-Subject: [virt-devel] [RHEL/RHEV-7 qemu-kvm(-rhev) EMBARGOED PATCH 1/3] ide:
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Check array bounds before writing to io_buffer (CVE-2015-5154)
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Bugzilla: 1243690
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RH-Acked-by: Petr Matousek <pmatouse@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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If the end_transfer_func of a command is called because enough data has
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been read or written for the current PIO transfer, and it fails to
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correctly call the command completion functions, the DRQ bit in the
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status register and s->end_transfer_func may remain set. This allows the
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guest to access further bytes in s->io_buffer beyond s->data_end, and
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eventually overflowing the io_buffer.
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One case where this currently happens is emulation of the ATAPI command
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START STOP UNIT.
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This patch fixes the problem by adding explicit array bounds checks
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before accessing the buffer instead of relying on end_transfer_func to
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function correctly.
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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hw/ide/core.c | 16 ++++++++++++++++
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1 file changed, 16 insertions(+)
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diff --git a/hw/ide/core.c b/hw/ide/core.c
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index d9fdb03..29bda6b 100644
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--- a/hw/ide/core.c
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+++ b/hw/ide/core.c
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@@ -1850,6 +1850,10 @@ void ide_data_writew(void *opaque, uint32_t addr, uint32_t val)
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}
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p = s->data_ptr;
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+ if (p + 2 > s->data_end) {
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+ return;
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+ }
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+
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*(uint16_t *)p = le16_to_cpu(val);
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p += 2;
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s->data_ptr = p;
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@@ -1871,6 +1875,10 @@ uint32_t ide_data_readw(void *opaque, uint32_t addr)
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}
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p = s->data_ptr;
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+ if (p + 2 > s->data_end) {
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+ return 0;
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+ }
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+
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ret = cpu_to_le16(*(uint16_t *)p);
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p += 2;
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s->data_ptr = p;
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@@ -1892,6 +1900,10 @@ void ide_data_writel(void *opaque, uint32_t addr, uint32_t val)
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}
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p = s->data_ptr;
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+ if (p + 4 > s->data_end) {
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+ return;
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+ }
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+
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*(uint32_t *)p = le32_to_cpu(val);
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p += 4;
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s->data_ptr = p;
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@@ -1913,6 +1925,10 @@ uint32_t ide_data_readl(void *opaque, uint32_t addr)
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}
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p = s->data_ptr;
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+ if (p + 4 > s->data_end) {
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+ return 0;
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+ }
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+
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ret = cpu_to_le32(*(uint32_t *)p);
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p += 4;
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s->data_ptr = p;
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--
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1.8.3.1
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