* [Qemu-devel] [PATCH] block: Fix use after free error in bdrv_open_inherit()
@ 2018-09-06 14:25 Alberto Garcia
2018-09-10 8:34 ` Kevin Wolf
0 siblings, 1 reply; 3+ messages in thread
From: Alberto Garcia @ 2018-09-06 14:25 UTC (permalink / raw)
To: qemu-devel; +Cc: Alberto Garcia, qemu-block, Kevin Wolf, Max Reitz, qemu-stable
When a block device is opened with BDRV_O_SNAPSHOT and the
bdrv_append_temp_snapshot() call fails then the error code path tries
to unref the already destroyed 'options' QDict.
This can be reproduced easily by setting TMPDIR to a location where
the QEMU process can't write:
$ TMPDIR=/nonexistent $QEMU -drive driver=null-co,snapshot=on
Signed-off-by: Alberto Garcia <berto@igalia.com>
---
block.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/block.c b/block.c
index 0dbb1fcc7b..a381c8ece8 100644
--- a/block.c
+++ b/block.c
@@ -2792,6 +2792,7 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
bdrv_parent_cb_change_media(bs, true);
qobject_unref(options);
+ options = NULL;
/* For snapshot=on, create a temporary qcow2 overlay. bs points to the
* temporary snapshot afterwards. */
--
2.11.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] block: Fix use after free error in bdrv_open_inherit()
2018-09-06 14:25 [Qemu-devel] [PATCH] block: Fix use after free error in bdrv_open_inherit() Alberto Garcia
@ 2018-09-10 8:34 ` Kevin Wolf
2018-09-10 9:34 ` Alberto Garcia
0 siblings, 1 reply; 3+ messages in thread
From: Kevin Wolf @ 2018-09-10 8:34 UTC (permalink / raw)
To: Alberto Garcia; +Cc: qemu-devel, qemu-block, Max Reitz, qemu-stable
Am 06.09.2018 um 16:25 hat Alberto Garcia geschrieben:
> When a block device is opened with BDRV_O_SNAPSHOT and the
> bdrv_append_temp_snapshot() call fails then the error code path tries
> to unref the already destroyed 'options' QDict.
>
> This can be reproduced easily by setting TMPDIR to a location where
> the QEMU process can't write:
>
> $ TMPDIR=/nonexistent $QEMU -drive driver=null-co,snapshot=on
>
> Signed-off-by: Alberto Garcia <berto@igalia.com>
Thanks, applied to the block branch.
But can we add the reproducer to some iotests case?
Kevin
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] block: Fix use after free error in bdrv_open_inherit()
2018-09-10 8:34 ` Kevin Wolf
@ 2018-09-10 9:34 ` Alberto Garcia
0 siblings, 0 replies; 3+ messages in thread
From: Alberto Garcia @ 2018-09-10 9:34 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block, Max Reitz, qemu-stable
On Mon 10 Sep 2018 10:34:20 AM CEST, Kevin Wolf <kwolf@redhat.com> wrote:
> Am 06.09.2018 um 16:25 hat Alberto Garcia geschrieben:
>> When a block device is opened with BDRV_O_SNAPSHOT and the
>> bdrv_append_temp_snapshot() call fails then the error code path tries
>> to unref the already destroyed 'options' QDict.
>>
>> This can be reproduced easily by setting TMPDIR to a location where
>> the QEMU process can't write:
>>
>> $ TMPDIR=/nonexistent $QEMU -drive driver=null-co,snapshot=on
>>
>> Signed-off-by: Alberto Garcia <berto@igalia.com>
>
> Thanks, applied to the block branch.
>
> But can we add the reproducer to some iotests case?
Yup, I just sent it.
Berto
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-09-06 14:25 [Qemu-devel] [PATCH] block: Fix use after free error in bdrv_open_inherit() Alberto Garcia
2018-09-10 8:34 ` Kevin Wolf
2018-09-10 9:34 ` Alberto Garcia
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