File ide-atapi-assert-that-the-buffer-pointer.patch of Package qemu.28164

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File ide-atapi-assert-that-the-buffer-pointer.patch of Package qemu.28164

From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 1 Dec 2020 13:09:26 +0100
Subject: ide: atapi: assert that the buffer pointer is in range

Git-commit: 813212288970c39b1800f63e83ac6e96588095c6
References: bsc#1181108, CVE-2020-29443

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>
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/ide/atapi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
index 17a9d635d8426684512d2a37bfa6..5e9a60c4595262a451cdacf75fdf 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

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File ide-atapi-assert-that-the-buffer-pointer.patch of Package qemu.28164

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