175 lines
4.9 KiB
Diff
175 lines
4.9 KiB
Diff
From a9de14175548c04e0f8be7fae219246509ba46a9 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Wed, 3 Jun 2015 14:13:31 +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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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 122e955..44fcc23 100644
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--- hw/ide/core.c
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+++ hw/ide/core.c
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@@ -2021,6 +2021,10 @@ 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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@@ -2042,6 +2046,10 @@ 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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@@ -2063,6 +2071,10 @@ 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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@@ -2084,6 +2096,10 @@ 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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From aa851d30acfbb9580098ac1dc82885530cb8b3c1 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Wed, 3 Jun 2015 14:17:46 +0200
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Subject: [PATCH 2/3] ide/atapi: Fix START STOP UNIT command completion
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The command must be completed on all code paths. START STOP UNIT with
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pwrcnd set should succeed without doing anything.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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hw/ide/atapi.c | 1 +
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1 file changed, 1 insertion(+)
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diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
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index 950e311..79dd167 100644
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--- hw/ide/atapi.c
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+++ hw/ide/atapi.c
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@@ -983,6 +983,7 @@ static void cmd_start_stop_unit(IDEState *s, uint8_t* buf)
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if (pwrcnd) {
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/* eject/load only happens for power condition == 0 */
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+ ide_atapi_cmd_ok(s);
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return;
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}
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--
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1.8.3.1
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From 1d3c2268f8708126a34064c2e0c1000b40e6f3e5 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Wed, 3 Jun 2015 14:41:27 +0200
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Subject: [PATCH 3/3] ide: Clear DRQ after handling all expected accesses
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This is additional hardening against an end_transfer_func that fails to
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clear the DRQ status bit. The bit must be unset as soon as the PIO
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transfer has completed, so it's better to do this in a central place
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instead of duplicating the code in all commands (and forgetting it in
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some).
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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, 12 insertions(+), 4 deletions(-)
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diff --git a/hw/ide/core.c b/hw/ide/core.c
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index 44fcc23..50449ca 100644
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--- hw/ide/core.c
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+++ hw/ide/core.c
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@@ -2028,8 +2028,10 @@ void ide_data_writew(void *opaque, uint32_t addr, uint32_t val)
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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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- if (p >= s->data_end)
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+ if (p >= s->data_end) {
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+ s->status &= ~DRQ_STAT;
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s->end_transfer_func(s);
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+ }
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}
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uint32_t ide_data_readw(void *opaque, uint32_t addr)
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@@ -2053,8 +2055,10 @@ uint32_t ide_data_readw(void *opaque, uint32_t addr)
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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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- if (p >= s->data_end)
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+ if (p >= s->data_end) {
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+ s->status &= ~DRQ_STAT;
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s->end_transfer_func(s);
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+ }
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return ret;
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}
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@@ -2078,8 +2082,10 @@ void ide_data_writel(void *opaque, uint32_t addr, uint32_t val)
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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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- if (p >= s->data_end)
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+ if (p >= s->data_end) {
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+ s->status &= ~DRQ_STAT;
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s->end_transfer_func(s);
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+ }
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}
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uint32_t ide_data_readl(void *opaque, uint32_t addr)
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@@ -2103,8 +2109,10 @@ uint32_t ide_data_readl(void *opaque, uint32_t addr)
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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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- if (p >= s->data_end)
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+ if (p >= s->data_end) {
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+ s->status &= ~DRQ_STAT;
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s->end_transfer_func(s);
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+ }
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return ret;
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}
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--
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1.8.3.1
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