* [Qemu-devel] [PATCH v2] qemu-img: initialize MapEntry object
@ 2016-02-05 18:12 John Snow
2016-02-05 19:56 ` Eric Blake
0 siblings, 1 reply; 3+ messages in thread
From: John Snow @ 2016-02-05 18:12 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, John Snow, famz, qemu-devel
Commit 16b0d555 introduced an issue where we are not initializing
has_filename for the 'next' MapEntry object, which leads to interesting
errors in Valgrind and Clang -fsanitize=undefined both.
Zero the stack object at allocation AND make sure the utility to
populate the fields properly marks has_filename as false if applicable.
Signed-off-by: John Snow <jsnow@redhat.com>
---
v2: Initialize with a compound literal as a future-proofing measure.
qemu-img.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)
diff --git a/qemu-img.c b/qemu-img.c
index f121980..4617d3b 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2195,6 +2195,7 @@ static int get_block_status(BlockDriverState *bs, int64_t sector_num,
int64_t ret;
int depth;
BlockDriverState *file;
+ bool has_offset;
/* As an optimization, we could cache the current range of unallocated
* clusters in each file of the chain, and avoid querying the same
@@ -2221,17 +2222,20 @@ static int get_block_status(BlockDriverState *bs, int64_t sector_num,
depth++;
}
- e->start = sector_num * BDRV_SECTOR_SIZE;
- e->length = nb_sectors * BDRV_SECTOR_SIZE;
- e->data = !!(ret & BDRV_BLOCK_DATA);
- e->zero = !!(ret & BDRV_BLOCK_ZERO);
- e->offset = ret & BDRV_BLOCK_OFFSET_MASK;
- e->has_offset = !!(ret & BDRV_BLOCK_OFFSET_VALID);
- e->depth = depth;
- if (file && e->has_offset) {
- e->has_filename = true;
- e->filename = file->filename;
- }
+ has_offset = !!(ret & BDRV_BLOCK_OFFSET_VALID);
+
+ *e = (MapEntry) {
+ .start = sector_num * BDRV_SECTOR_SIZE,
+ .length = nb_sectors * BDRV_SECTOR_SIZE,
+ .data = !!(ret & BDRV_BLOCK_DATA),
+ .zero = !!(ret & BDRV_BLOCK_ZERO),
+ .offset = ret & BDRV_BLOCK_OFFSET_MASK,
+ .has_offset = has_offset,
+ .depth = depth,
+ .has_filename = file && has_offset,
+ .filename = file && has_offset ? file->filename : NULL,
+ };
+
return 0;
}
--
2.4.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH v2] qemu-img: initialize MapEntry object
2016-02-05 18:12 [Qemu-devel] [PATCH v2] qemu-img: initialize MapEntry object John Snow
@ 2016-02-05 19:56 ` Eric Blake
2016-02-12 14:31 ` Kevin Wolf
0 siblings, 1 reply; 3+ messages in thread
From: Eric Blake @ 2016-02-05 19:56 UTC (permalink / raw)
To: John Snow, qemu-block; +Cc: kwolf, famz, qemu-devel
[-- Attachment #1: Type: text/plain, Size: 757 bytes --]
On 02/05/2016 11:12 AM, John Snow wrote:
> Commit 16b0d555 introduced an issue where we are not initializing
> has_filename for the 'next' MapEntry object, which leads to interesting
> errors in Valgrind and Clang -fsanitize=undefined both.
grammar:
errors in both Valgrind and Clang -fsanitize=undefined.
>
> Zero the stack object at allocation AND make sure the utility to
> populate the fields properly marks has_filename as false if applicable.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
> v2: Initialize with a compound literal as a future-proofing measure.
>
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH v2] qemu-img: initialize MapEntry object
2016-02-05 19:56 ` Eric Blake
@ 2016-02-12 14:31 ` Kevin Wolf
0 siblings, 0 replies; 3+ messages in thread
From: Kevin Wolf @ 2016-02-12 14:31 UTC (permalink / raw)
To: Eric Blake; +Cc: famz, John Snow, qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 796 bytes --]
Am 05.02.2016 um 20:56 hat Eric Blake geschrieben:
> On 02/05/2016 11:12 AM, John Snow wrote:
> > Commit 16b0d555 introduced an issue where we are not initializing
> > has_filename for the 'next' MapEntry object, which leads to interesting
> > errors in Valgrind and Clang -fsanitize=undefined both.
>
> grammar:
>
> errors in both Valgrind and Clang -fsanitize=undefined.
Fixed up.
> >
> > Zero the stack object at allocation AND make sure the utility to
> > populate the fields properly marks has_filename as false if applicable.
> >
> > Signed-off-by: John Snow <jsnow@redhat.com>
> > ---
> > v2: Initialize with a compound literal as a future-proofing measure.
> >
>
> Reviewed-by: Eric Blake <eblake@redhat.com>
Thanks, applied to the block branch.
Kevin
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^ permalink raw reply [flat|nested] 3+ messages in thread
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