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m 813212288970c39b1800f63e83ac6e96588095c6 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 1 Dec 2020 13:09:26 +0100
Subject: [PATCH] ide: atapi: assert that the buffer pointer is in range
A case was reported where s->io_buffer_index can be out of range.
The report skimped on the details but it seems to be triggered
by s->lba == -1 on the READ/READ CD paths (e.g. by sending an
ATAPI command with LBA = 0xFFFFFFFF). For now paper over it
with assertions. The first one ensures that there is no overflow
when incrementing s->io_buffer_index, the second checks for the
buffer overrun.
Note that the buffer overrun is only a read, so I am not sure
if the assertion failure is actually less harmful than the overrun.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20201201120926.56559-1-pbonzini@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Upstream-Status: Backport [https://git.qemu.org/?p=qemu.git;a=patch;h=813212288970c39b1800f63e83ac6e96588095c6]
CVE: CVE-2020-29443
Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com>
---
hw/ide/atapi.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
index 14a2b0b..e791578 100644
--- a/hw/ide/atapi.c
+++ b/hw/ide/atapi.c
@@ -276,6 +276,8 @@ void ide_atapi_cmd_reply_end(IDEState *s)
s->packet_transfer_size -= size;
s->elementary_transfer_size -= size;
s->io_buffer_index += size;
+ assert(size <= s->io_buffer_total_len);
+ assert(s->io_buffer_index <= s->io_buffer_total_len);
/* Some adapters process PIO data right away. In that case, we need
* to avoid mutual recursion between ide_transfer_start
--
1.8.3.1
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