* [Qemu-devel] [PATCH] qcow2: Zero-initialise first cluster for new images
@ 2013-11-26 10:48 Kevin Wolf
2013-11-26 12:18 ` [Qemu-devel] [Qemu-stable] " Fam Zheng
2013-11-27 11:18 ` [Qemu-devel] " Paolo Bonzini
0 siblings, 2 replies; 4+ messages in thread
From: Kevin Wolf @ 2013-11-26 10:48 UTC (permalink / raw)
To: qemu-devel; +Cc: kwolf, qemu-stable, stefanha
Strictly speaking, this is only required for has_zero_init() == false,
but it's easy enough to just do a cluster-aligned write that is padded
with zeros after the header.
This fixes that after 'qemu-img create' header extensions are attempted
to be parsed that are really just random leftover data.
Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/qcow2.c | 37 +++++++++++++++++++++----------------
1 file changed, 21 insertions(+), 16 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index 6e5d98d..7c18587 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1471,7 +1471,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
* size for any qcow2 image.
*/
BlockDriverState* bs;
- QCowHeader header;
+ QCowHeader *header;
uint8_t* refcount_table;
Error *local_err = NULL;
int ret;
@@ -1489,30 +1489,35 @@ static int qcow2_create2(const char *filename, int64_t total_size,
}
/* Write the header */
- memset(&header, 0, sizeof(header));
- header.magic = cpu_to_be32(QCOW_MAGIC);
- header.version = cpu_to_be32(version);
- header.cluster_bits = cpu_to_be32(cluster_bits);
- header.size = cpu_to_be64(0);
- header.l1_table_offset = cpu_to_be64(0);
- header.l1_size = cpu_to_be32(0);
- header.refcount_table_offset = cpu_to_be64(cluster_size);
- header.refcount_table_clusters = cpu_to_be32(1);
- header.refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT);
- header.header_length = cpu_to_be32(sizeof(header));
+ QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
+ header = g_malloc(cluster_size);
+ memset(header, 0, cluster_size);
+ *header = (QCowHeader) {
+ .magic = cpu_to_be32(QCOW_MAGIC),
+ .version = cpu_to_be32(version),
+ .cluster_bits = cpu_to_be32(cluster_bits),
+ .size = cpu_to_be64(0),
+ .l1_table_offset = cpu_to_be64(0),
+ .l1_size = cpu_to_be32(0),
+ .refcount_table_offset = cpu_to_be64(cluster_size),
+ .refcount_table_clusters = cpu_to_be32(1),
+ .refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT),
+ .header_length = cpu_to_be32(sizeof(*header)),
+ };
if (flags & BLOCK_FLAG_ENCRYPT) {
- header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
+ header->crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
} else {
- header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
+ header->crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
}
if (flags & BLOCK_FLAG_LAZY_REFCOUNTS) {
- header.compatible_features |=
+ header->compatible_features |=
cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
}
- ret = bdrv_pwrite(bs, 0, &header, sizeof(header));
+ ret = bdrv_pwrite(bs, 0, header, cluster_size);
+ g_free(header);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not write qcow2 header");
goto out;
--
1.8.1.4
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [Qemu-stable] [PATCH] qcow2: Zero-initialise first cluster for new images
2013-11-26 10:48 [Qemu-devel] [PATCH] qcow2: Zero-initialise first cluster for new images Kevin Wolf
@ 2013-11-26 12:18 ` Fam Zheng
2013-11-27 12:44 ` Kevin Wolf
2013-11-27 11:18 ` [Qemu-devel] " Paolo Bonzini
1 sibling, 1 reply; 4+ messages in thread
From: Fam Zheng @ 2013-11-26 12:18 UTC (permalink / raw)
To: Kevin Wolf, qemu-devel; +Cc: qemu-stable, stefanha
On 2013年11月26日 18:48, Kevin Wolf wrote:
> Strictly speaking, this is only required for has_zero_init() == false,
> but it's easy enough to just do a cluster-aligned write that is padded
> with zeros after the header.
>
> This fixes that after 'qemu-img create' header extensions are attempted
> to be parsed that are really just random leftover data.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> block/qcow2.c | 37 +++++++++++++++++++++----------------
> 1 file changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 6e5d98d..7c18587 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -1471,7 +1471,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
> * size for any qcow2 image.
> */
> BlockDriverState* bs;
> - QCowHeader header;
> + QCowHeader *header;
> uint8_t* refcount_table;
> Error *local_err = NULL;
> int ret;
> @@ -1489,30 +1489,35 @@ static int qcow2_create2(const char *filename, int64_t total_size,
> }
>
> /* Write the header */
> - memset(&header, 0, sizeof(header));
> - header.magic = cpu_to_be32(QCOW_MAGIC);
> - header.version = cpu_to_be32(version);
> - header.cluster_bits = cpu_to_be32(cluster_bits);
> - header.size = cpu_to_be64(0);
> - header.l1_table_offset = cpu_to_be64(0);
> - header.l1_size = cpu_to_be32(0);
> - header.refcount_table_offset = cpu_to_be64(cluster_size);
> - header.refcount_table_clusters = cpu_to_be32(1);
> - header.refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT);
> - header.header_length = cpu_to_be32(sizeof(header));
> + QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
> + header = g_malloc(cluster_size);
> + memset(header, 0, cluster_size);
Could just be:
header = g_malloc0(cluster_size);
But either way,
Reviewed-by: Fam Zheng <famz@redhat.com>
> + *header = (QCowHeader) {
> + .magic = cpu_to_be32(QCOW_MAGIC),
> + .version = cpu_to_be32(version),
> + .cluster_bits = cpu_to_be32(cluster_bits),
> + .size = cpu_to_be64(0),
> + .l1_table_offset = cpu_to_be64(0),
> + .l1_size = cpu_to_be32(0),
> + .refcount_table_offset = cpu_to_be64(cluster_size),
> + .refcount_table_clusters = cpu_to_be32(1),
> + .refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT),
> + .header_length = cpu_to_be32(sizeof(*header)),
> + };
>
> if (flags & BLOCK_FLAG_ENCRYPT) {
> - header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
> + header->crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
> } else {
> - header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
> + header->crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
> }
>
> if (flags & BLOCK_FLAG_LAZY_REFCOUNTS) {
> - header.compatible_features |=
> + header->compatible_features |=
> cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
> }
>
> - ret = bdrv_pwrite(bs, 0, &header, sizeof(header));
> + ret = bdrv_pwrite(bs, 0, header, cluster_size);
> + g_free(header);
> if (ret < 0) {
> error_setg_errno(errp, -ret, "Could not write qcow2 header");
> goto out;
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [Qemu-stable] [PATCH] qcow2: Zero-initialise first cluster for new images
2013-11-26 12:18 ` [Qemu-devel] [Qemu-stable] " Fam Zheng
@ 2013-11-27 12:44 ` Kevin Wolf
0 siblings, 0 replies; 4+ messages in thread
From: Kevin Wolf @ 2013-11-27 12:44 UTC (permalink / raw)
To: Fam Zheng; +Cc: qemu-devel, stefanha, qemu-stable
Am 26.11.2013 um 13:18 hat Fam Zheng geschrieben:
> On 2013年11月26日 18:48, Kevin Wolf wrote:
> >Strictly speaking, this is only required for has_zero_init() == false,
> >but it's easy enough to just do a cluster-aligned write that is padded
> >with zeros after the header.
> >
> >This fixes that after 'qemu-img create' header extensions are attempted
> >to be parsed that are really just random leftover data.
> >
> >Cc: qemu-stable@nongnu.org
> >Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> >---
> > block/qcow2.c | 37 +++++++++++++++++++++----------------
> > 1 file changed, 21 insertions(+), 16 deletions(-)
> >
> >diff --git a/block/qcow2.c b/block/qcow2.c
> >index 6e5d98d..7c18587 100644
> >--- a/block/qcow2.c
> >+++ b/block/qcow2.c
> >@@ -1471,7 +1471,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
> > * size for any qcow2 image.
> > */
> > BlockDriverState* bs;
> >- QCowHeader header;
> >+ QCowHeader *header;
> > uint8_t* refcount_table;
> > Error *local_err = NULL;
> > int ret;
> >@@ -1489,30 +1489,35 @@ static int qcow2_create2(const char *filename, int64_t total_size,
> > }
> >
> > /* Write the header */
> >- memset(&header, 0, sizeof(header));
> >- header.magic = cpu_to_be32(QCOW_MAGIC);
> >- header.version = cpu_to_be32(version);
> >- header.cluster_bits = cpu_to_be32(cluster_bits);
> >- header.size = cpu_to_be64(0);
> >- header.l1_table_offset = cpu_to_be64(0);
> >- header.l1_size = cpu_to_be32(0);
> >- header.refcount_table_offset = cpu_to_be64(cluster_size);
> >- header.refcount_table_clusters = cpu_to_be32(1);
> >- header.refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT);
> >- header.header_length = cpu_to_be32(sizeof(header));
> >+ QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
> >+ header = g_malloc(cluster_size);
> >+ memset(header, 0, cluster_size);
>
> Could just be:
>
> header = g_malloc0(cluster_size);
>
> But either way,
Yes, that's better. I'll change it.
> Reviewed-by: Fam Zheng <famz@redhat.com>
Thanks.
Kevin
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH] qcow2: Zero-initialise first cluster for new images
2013-11-26 10:48 [Qemu-devel] [PATCH] qcow2: Zero-initialise first cluster for new images Kevin Wolf
2013-11-26 12:18 ` [Qemu-devel] [Qemu-stable] " Fam Zheng
@ 2013-11-27 11:18 ` Paolo Bonzini
1 sibling, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2013-11-27 11:18 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, stefanha, qemu-stable
Il 26/11/2013 11:48, Kevin Wolf ha scritto:
> Strictly speaking, this is only required for has_zero_init() == false,
> but it's easy enough to just do a cluster-aligned write that is padded
> with zeros after the header.
>
> This fixes that after 'qemu-img create' header extensions are attempted
> to be parsed that are really just random leftover data.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> block/qcow2.c | 37 +++++++++++++++++++++----------------
> 1 file changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 6e5d98d..7c18587 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -1471,7 +1471,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
> * size for any qcow2 image.
> */
> BlockDriverState* bs;
> - QCowHeader header;
> + QCowHeader *header;
> uint8_t* refcount_table;
> Error *local_err = NULL;
> int ret;
> @@ -1489,30 +1489,35 @@ static int qcow2_create2(const char *filename, int64_t total_size,
> }
>
> /* Write the header */
> - memset(&header, 0, sizeof(header));
> - header.magic = cpu_to_be32(QCOW_MAGIC);
> - header.version = cpu_to_be32(version);
> - header.cluster_bits = cpu_to_be32(cluster_bits);
> - header.size = cpu_to_be64(0);
> - header.l1_table_offset = cpu_to_be64(0);
> - header.l1_size = cpu_to_be32(0);
> - header.refcount_table_offset = cpu_to_be64(cluster_size);
> - header.refcount_table_clusters = cpu_to_be32(1);
> - header.refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT);
> - header.header_length = cpu_to_be32(sizeof(header));
> + QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
> + header = g_malloc(cluster_size);
> + memset(header, 0, cluster_size);
> + *header = (QCowHeader) {
> + .magic = cpu_to_be32(QCOW_MAGIC),
> + .version = cpu_to_be32(version),
> + .cluster_bits = cpu_to_be32(cluster_bits),
> + .size = cpu_to_be64(0),
> + .l1_table_offset = cpu_to_be64(0),
> + .l1_size = cpu_to_be32(0),
> + .refcount_table_offset = cpu_to_be64(cluster_size),
> + .refcount_table_clusters = cpu_to_be32(1),
> + .refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT),
> + .header_length = cpu_to_be32(sizeof(*header)),
> + };
>
> if (flags & BLOCK_FLAG_ENCRYPT) {
> - header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
> + header->crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
> } else {
> - header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
> + header->crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
> }
>
> if (flags & BLOCK_FLAG_LAZY_REFCOUNTS) {
> - header.compatible_features |=
> + header->compatible_features |=
> cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
> }
>
> - ret = bdrv_pwrite(bs, 0, &header, sizeof(header));
> + ret = bdrv_pwrite(bs, 0, header, cluster_size);
> + g_free(header);
> if (ret < 0) {
> error_setg_errno(errp, -ret, "Could not write qcow2 header");
> goto out;
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-11-27 12:44 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-11-26 10:48 [Qemu-devel] [PATCH] qcow2: Zero-initialise first cluster for new images Kevin Wolf
2013-11-26 12:18 ` [Qemu-devel] [Qemu-stable] " Fam Zheng
2013-11-27 12:44 ` Kevin Wolf
2013-11-27 11:18 ` [Qemu-devel] " Paolo Bonzini
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).