[Qemu-devel] [PATCH for-2.3 v2 0/6] vmdk: A few small fixes

[Qemu-devel] [PATCH for-2.3 v2 0/6] vmdk: A few small fixes

[Fam Zheng]

v2: 3/6: Don't overwrite the last byte of buffer. (Don)
    Other patches are unchanged (added Markus' rev-by line).

Here are some improvements on miscellaneous things such as CID generation,
comments, input validation.


Fam Zheng (6):
  vmdk: Use g_random_int to generate CID
  vmdk: Fix comment to match code of extent lines
  vmdk: Clean up descriptor file reading
  vmdk: Check descriptor file length when reading it
  vmdk: Remove unnecessary initialization
  vmdk: Set errp on failures in vmdk_open_vmdk4

 block/vmdk.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

-- 
1.9.3

[Qemu-devel] [PATCH for-2.3 v2 1/6] vmdk: Use g_random_int to generate CID

[Fam Zheng]

This replaces two "time(NULL)" invocations with "g_random_int()".
According to VMDK spec, CID "is a random 32‐bit value updated the first
time the content of the virtual disk is modified after the virtual disk
is opened". Using "seconds since epoch" is just a "lame way" to generate
it, and not completely safe because of the low precision.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
---
 block/vmdk.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 2cbfd3e..ebb4b70 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -28,6 +28,7 @@
 #include "qemu/module.h"
 #include "migration/migration.h"
 #include <zlib.h>
+#include <glib.h>
 
 #define VMDK3_MAGIC (('C' << 24) | ('O' << 16) | ('W' << 8) | 'D')
 #define VMDK4_MAGIC (('K' << 24) | ('D' << 16) | ('M' << 8) | 'V')
@@ -1538,7 +1539,7 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
         /* update CID on the first write every time the virtual disk is
          * opened */
         if (!s->cid_updated) {
-            ret = vmdk_write_cid(bs, time(NULL));
+            ret = vmdk_write_cid(bs, g_random_int());
             if (ret < 0) {
                 return ret;
             }
@@ -1922,7 +1923,7 @@ static int vmdk_create(const char *filename, QemuOpts *opts, Error **errp)
     }
     /* generate descriptor file */
     desc = g_strdup_printf(desc_template,
-                           (uint32_t)time(NULL),
+                           g_random_int(),
                            parent_cid,
                            fmt,
                            parent_desc_line,
-- 
1.9.3

[Qemu-devel] [PATCH for-2.3 v2 2/6] vmdk: Fix comment to match code of extent lines

[Fam Zheng]

commit 04d542c8b (vmdk: support vmfs files) added support of VMFS extent
type but the comment above the changed code is left out. Update the
comment so they are consistent.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
---
 block/vmdk.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index ebb4b70..28d22db 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -785,10 +785,11 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
     VmdkExtent *extent;
 
     while (*p) {
-        /* parse extent line:
+        /* parse extent line in one of below formats:
+         *
          * RW [size in sectors] FLAT "file-name.vmdk" OFFSET
-         * or
          * RW [size in sectors] SPARSE "file-name.vmdk"
+         * RW [size in sectors] VMFS "file-name.vmdk"
          */
         flat_offset = -1;
         ret = sscanf(p, "%10s %" SCNd64 " %10s \"%511[^\n\r\"]\" %" SCNd64,
-- 
1.9.3

[Qemu-devel] [PATCH for-2.3 v2 3/6] vmdk: Clean up descriptor file reading

[Fam Zheng]

Zeroing a buffer that will be filled right after is not necessary, and
allocating a power of two + 1 is naughty.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 28d22db..e863a09 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -558,14 +558,15 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
     }
 
     size = MIN(size, 1 << 20);  /* avoid unbounded allocation */
-    buf = g_malloc0(size + 1);
+    buf = g_malloc(size);
 
-    ret = bdrv_pread(file, desc_offset, buf, size);
+    ret = bdrv_pread(file, desc_offset, buf, size - 1);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not read from file");
         g_free(buf);
         return NULL;
     }
+    buf[ret] = 0;
 
     return buf;
 }
-- 
1.9.3

Re: [Qemu-devel] [PATCH for-2.3 v2 3/6] vmdk: Clean up descriptor file reading

[Markus Armbruster]

Fam Zheng <famz@redhat.com> writes:

> Zeroing a buffer that will be filled right after is not necessary, and
> allocating a power of two + 1 is naughty.
>
> Suggested-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block/vmdk.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 28d22db..e863a09 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -558,14 +558,15 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
>      }
>  
       size = bdrv_getlength(file);
       if (size < 0) {
           error_setg_errno(errp, -size, "Could not access file");
           return NULL;
       }

>      size = MIN(size, 1 << 20);  /* avoid unbounded allocation */

Consider the case where size <= 1 << 20, i.e. this line is a no-op.

> -    buf = g_malloc0(size + 1);
> +    buf = g_malloc(size);
>  
> -    ret = bdrv_pread(file, desc_offset, buf, size);
> +    ret = bdrv_pread(file, desc_offset, buf, size - 1);

Then this reads everything except the last byte (thanks to Don for
spotting it).

>      if (ret < 0) {
>          error_setg_errno(errp, -ret, "Could not read from file");
>          g_free(buf);
>          return NULL;
>      }
> +    buf[ret] = 0;
>  
>      return buf;
>  }

I figure Don suggested this instead:

diff --git a/block/vmdk.c b/block/vmdk.c
index 2cbfd3e..b7feb15 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -556,8 +556,8 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
         return NULL;
     }
 
-    size = MIN(size, 1 << 20);  /* avoid unbounded allocation */
-    buf = g_malloc0(size + 1);
+    size = MIN(size, (1 << 20) - 1);  /* avoid unbounded allocation */
+    buf = g_malloc(size + 1);
 
     ret = bdrv_pread(file, desc_offset, buf, size);
     if (ret < 0) {
@@ -565,6 +565,7 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
         g_free(buf);
         return NULL;
     }
+    buf[ret] = 0;
 
     return buf;
 }

Re: [Qemu-devel] [PATCH for-2.3 v2 3/6] vmdk: Clean up descriptor file reading

[Fam Zheng]

On Wed, 12/03 09:21, Markus Armbruster wrote:
> Fam Zheng <famz@redhat.com> writes:
> 
> > Zeroing a buffer that will be filled right after is not necessary, and
> > allocating a power of two + 1 is naughty.
> >
> > Suggested-by: Markus Armbruster <armbru@redhat.com>
> > Signed-off-by: Fam Zheng <famz@redhat.com>
> > ---
> >  block/vmdk.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/block/vmdk.c b/block/vmdk.c
> > index 28d22db..e863a09 100644
> > --- a/block/vmdk.c
> > +++ b/block/vmdk.c
> > @@ -558,14 +558,15 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
> >      }
> >  
>        size = bdrv_getlength(file);
>        if (size < 0) {
>            error_setg_errno(errp, -size, "Could not access file");
>            return NULL;
>        }
> 
> >      size = MIN(size, 1 << 20);  /* avoid unbounded allocation */
> 
> Consider the case where size <= 1 << 20, i.e. this line is a no-op.
> 
> > -    buf = g_malloc0(size + 1);
> > +    buf = g_malloc(size);
> >  
> > -    ret = bdrv_pread(file, desc_offset, buf, size);
> > +    ret = bdrv_pread(file, desc_offset, buf, size - 1);
> 
> Then this reads everything except the last byte (thanks to Don for
> spotting it).

Yes, I was wrong.

> 
> >      if (ret < 0) {
> >          error_setg_errno(errp, -ret, "Could not read from file");
> >          g_free(buf);
> >          return NULL;
> >      }
> > +    buf[ret] = 0;
> >  
> >      return buf;
> >  }
> 
> I figure Don suggested this instead:

Yes. Thanks.

Fam

> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 2cbfd3e..b7feb15 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -556,8 +556,8 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
>          return NULL;
>      }
>  
> -    size = MIN(size, 1 << 20);  /* avoid unbounded allocation */
> -    buf = g_malloc0(size + 1);
> +    size = MIN(size, (1 << 20) - 1);  /* avoid unbounded allocation */
> +    buf = g_malloc(size + 1);
>  
>      ret = bdrv_pread(file, desc_offset, buf, size);
>      if (ret < 0) {
> @@ -565,6 +565,7 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
>          g_free(buf);
>          return NULL;
>      }
> +    buf[ret] = 0;
>  
>      return buf;
>  }

Re: [Qemu-devel] [PATCH for-2.3 v2 3/6] vmdk: Clean up descriptor file reading

[Don Koch]

On Wed, 3 Dec 2014 17:20:27 +0800
Fam Zheng <famz@redhat.com> wrote:

> On Wed, 12/03 09:21, Markus Armbruster wrote:
> > Fam Zheng <famz@redhat.com> writes:
> > 
> > > Zeroing a buffer that will be filled right after is not necessary, and
> > > allocating a power of two + 1 is naughty.
> > >
> > > Suggested-by: Markus Armbruster <armbru@redhat.com>
> > > Signed-off-by: Fam Zheng <famz@redhat.com>
> > > ---
> > >  block/vmdk.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/block/vmdk.c b/block/vmdk.c
> > > index 28d22db..e863a09 100644
> > > --- a/block/vmdk.c
> > > +++ b/block/vmdk.c
> > > @@ -558,14 +558,15 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
> > >      }
> > >  
> >        size = bdrv_getlength(file);
> >        if (size < 0) {
> >            error_setg_errno(errp, -size, "Could not access file");
> >            return NULL;
> >        }
> > 
> > >      size = MIN(size, 1 << 20);  /* avoid unbounded allocation */
> > 
> > Consider the case where size <= 1 << 20, i.e. this line is a no-op.
> > 
> > > -    buf = g_malloc0(size + 1);
> > > +    buf = g_malloc(size);
> > >  
> > > -    ret = bdrv_pread(file, desc_offset, buf, size);
> > > +    ret = bdrv_pread(file, desc_offset, buf, size - 1);
> > 
> > Then this reads everything except the last byte (thanks to Don for
> > spotting it).
> 
> Yes, I was wrong.
> 
> > 
> > >      if (ret < 0) {
> > >          error_setg_errno(errp, -ret, "Could not read from file");
> > >          g_free(buf);
> > >          return NULL;
> > >      }
> > > +    buf[ret] = 0;
> > >  
> > >      return buf;
> > >  }
> > 
> > I figure Don suggested this instead:

Correct.

> 
> Yes. Thanks.
> 
> Fam
> 
> > 
> > diff --git a/block/vmdk.c b/block/vmdk.c
> > index 2cbfd3e..b7feb15 100644
> > --- a/block/vmdk.c
> > +++ b/block/vmdk.c
> > @@ -556,8 +556,8 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
> >          return NULL;
> >      }
> >  
> > -    size = MIN(size, 1 << 20);  /* avoid unbounded allocation */
> > -    buf = g_malloc0(size + 1);
> > +    size = MIN(size, (1 << 20) - 1);  /* avoid unbounded allocation */
> > +    buf = g_malloc(size + 1);
> >  
> >      ret = bdrv_pread(file, desc_offset, buf, size);
> >      if (ret < 0) {
> > @@ -565,6 +565,7 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
> >          g_free(buf);
> >          return NULL;
> >      }
> > +    buf[ret] = 0;
> >  
> >      return buf;
> >  }
> 

-d

[Qemu-devel] [PATCH for-2.3 v2 4/6] vmdk: Check descriptor file length when reading it

[Fam Zheng]

Since a too small file cannot be a valid VMDK image, and also since the
buffer's first 4 bytes will be unconditionally examined by
vmdk_open_sparse, let's error out the small file case to be clear.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
---
 block/vmdk.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block/vmdk.c b/block/vmdk.c
index e863a09..b051adc 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -557,6 +557,11 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
         return NULL;
     }
 
+    if (size < 4) {
+        error_setg_errno(errp, -size, "File is too small, not a valid image");
+        return NULL;
+    }
+
     size = MIN(size, 1 << 20);  /* avoid unbounded allocation */
     buf = g_malloc(size);
 
-- 
1.9.3

[Qemu-devel] [PATCH for-2.3 v2 5/6] vmdk: Remove unnecessary initialization

[Fam Zheng]

It will be assigned to the return value of vmdk_read_desc.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
---
 block/vmdk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index b051adc..cde1870 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -910,7 +910,7 @@ exit:
 static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
 {
-    char *buf = NULL;
+    char *buf;
     int ret;
     BDRVVmdkState *s = bs->opaque;
     uint32_t magic;
-- 
1.9.3

[Qemu-devel] [PATCH for-2.3 v2 6/6] vmdk: Set errp on failures in vmdk_open_vmdk4

[Fam Zheng]

Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
---
 block/vmdk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/block/vmdk.c b/block/vmdk.c
index cde1870..6df0472 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -642,6 +642,7 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
             bs->file->total_sectors * 512 - 1536,
             &footer, sizeof(footer));
         if (ret < 0) {
+            error_setg_errno(errp, -ret, "Failed to read footer");
             return ret;
         }
 
@@ -653,6 +654,7 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
             le32_to_cpu(footer.eos_marker.size) != 0  ||
             le32_to_cpu(footer.eos_marker.type) != MARKER_END_OF_STREAM)
         {
+            error_setg(errp, "Invalid footer");
             return -EINVAL;
         }
 
@@ -683,6 +685,7 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
     l1_entry_sectors = le32_to_cpu(header.num_gtes_per_gt)
                         * le64_to_cpu(header.granularity);
     if (l1_entry_sectors == 0) {
+        error_setg(errp, "L1 entry size is invalid");
         return -EINVAL;
     }
     l1_size = (le64_to_cpu(header.capacity) + l1_entry_sectors - 1)
-- 
1.9.3