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CVE: fix CVE-2019-20175

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backport patch from upstream:
https://git.qemu.org/?p=qemu.git;a=commitdiff;h=ed78352a59ea7acf7520d4d47a96b9911bae7fc3

Signed-off-by: Ying Fang <fangying1@huawei.com>
This commit is contained in:
Ying Fang 2020-05-15 15:33:14 +08:00
parent b7d6ad34b1
commit f645d20455
2 changed files with 93 additions and 0 deletions
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89
ide-Fix-incorrect-handling-of-some-PRDTs-in-ide_dma_.patch Normal file
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@ -0,0 +1,89 @@
From ed78352a59ea7acf7520d4d47a96b9911bae7fc3 Mon Sep 17 00:00:00 2001
From: Alexander Popov <alex.popov@linux.com>
Date: Mon, 23 Dec 2019 20:51:16 +0300
Subject: [PATCH] ide: Fix incorrect handling of some PRDTs in ide_dma_cb()
The commit a718978ed58a from July 2015 introduced the assertion which
implies that the size of successful DMA transfers handled in ide_dma_cb()
should be multiple of 512 (the size of a sector). But guest systems can
initiate DMA transfers that don't fit this requirement.
For fixing that let's check the number of bytes prepared for the transfer
by the prepare_buf() handler. The code in ide_dma_cb() must behave
according to the Programming Interface for Bus Master IDE Controller
(Revision 1.0 5/16/94):
1. If PRDs specified a smaller size than the IDE transfer
size, then the Interrupt and Active bits in the Controller
status register are not set (Error Condition).
2. If the size of the physical memory regions was equal to
the IDE device transfer size, the Interrupt bit in the
Controller status register is set to 1, Active bit is set to 0.
3. If PRDs specified a larger size than the IDE transfer size,
the Interrupt and Active bits in the Controller status register
are both set to 1.
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 20191223175117.508990-2-alex.popov@linux.com
Signed-off-by: John Snow <jsnow@redhat.com>
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 754ff4dc34..80000eb766 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -849,6 +849,7 @@ static void ide_dma_cb(void *opaque, int ret)
int64_t sector_num;
uint64_t offset;
bool stay_active = false;
+ int32_t prep_size = 0;
if (ret == -EINVAL) {
ide_dma_error(s);
@@ -863,13 +864,15 @@ static void ide_dma_cb(void *opaque, int ret)
}
}
- n = s->io_buffer_size >> 9;
- if (n > s->nsector) {
- /* The PRDs were longer than needed for this request. Shorten them so
- * we don't get a negative remainder. The Active bit must remain set
- * after the request completes. */
+ if (s->io_buffer_size > s->nsector * 512) {
+ /*
+ * The PRDs were longer than needed for this request.
+ * The Active bit must remain set after the request completes.
+ */
n = s->nsector;
stay_active = true;
+ } else {
+ n = s->io_buffer_size >> 9;
}
sector_num = ide_get_sector(s);
@@ -892,9 +895,20 @@ static void ide_dma_cb(void *opaque, int ret)
n = s->nsector;
s->io_buffer_index = 0;
s->io_buffer_size = n * 512;
- if (s->bus->dma->ops->prepare_buf(s->bus->dma, s->io_buffer_size) < 512) {
- /* The PRDs were too short. Reset the Active bit, but don't raise an
- * interrupt. */
+ prep_size = s->bus->dma->ops->prepare_buf(s->bus->dma, s->io_buffer_size);
+ /* prepare_buf() must succeed and respect the limit */
+ assert(prep_size >= 0 && prep_size <= n * 512);
+
+ /*
+ * Now prep_size stores the number of bytes in the sglist, and
+ * s->io_buffer_size stores the number of bytes described by the PRDs.
+ */
+
+ if (prep_size < n * 512) {
+ /*
+ * The PRDs are too short for this request. Error condition!
+ * Reset the Active bit and don't raise the interrupt.
+ */
s->status = READY_STAT | SEEK_STAT;
dma_buf_commit(s, 0);
goto eot;
--
2.23.0

4
qemu.spec
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@ -162,6 +162,7 @@ Patch0149: migration-ram-Do-error_free-after-migrate_set_error-.patch
Patch0150: migration-ram-fix-memleaks-in-multifd_new_send_chann.patch
Patch0151: migration-rdma-fix-a-memleak-on-error-path-in-rdma_s.patch
Patch0152: arm-virt-Support-CPU-cold-plug.patch
Patch0153: ide-Fix-incorrect-handling-of-some-PRDTs-in-ide_dma_.patch
BuildRequires: flex
BuildRequires: bison
@ -507,6 +508,9 @@ getent passwd qemu >/dev/null || \
%endif
%changelog
* Fri May 15 2020 Huawei Technologies Co., Ltd. <fangying1@huawei.com>
- ide: Fix incorrect handling of some PRDTs in ide_dma_cb()
* Tue May 12 2020 Huawei Technologies Co., Ltd. <zhukeqian1@huawei.com>
- arm/virt: Support CPU cold plug