[Qemu-devel] [PATCH v2] util/id: fully allocate names table

[Qemu-devel] [PATCH v2] util/id: fully allocate names table

[John Snow]

Trivial: this array should be allocated to have ID_MAX entries always.
Otherwise if someone were to forget to expand this table, the assertion
in the id generator won't actually trigger; it will read junk data.

v2: Fix the range assertion, too. Compare against the known actual size
    of the table instead of what it "should" be.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 util/id.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/util/id.c b/util/id.c
index bcc64d8..7883fbe 100644
--- a/util/id.c
+++ b/util/id.c
@@ -29,7 +29,7 @@ bool id_wellformed(const char *id)
 
 #define ID_SPECIAL_CHAR '#'
 
-static const char *const id_subsys_str[] = {
+static const char *const id_subsys_str[ID_MAX] = {
     [ID_QDEV]  = "qdev",
     [ID_BLOCK] = "block",
 };
@@ -53,7 +53,7 @@ char *id_generate(IdSubSystems id)
     static uint64_t id_counters[ID_MAX];
     uint32_t rnd;
 
-    assert(id < ID_MAX);
+    assert(id < ARRAY_SIZE(id_subsys_str));
     assert(id_subsys_str[id]);
 
     rnd = g_random_int_range(0, 100);
-- 
2.4.3

Re: [Qemu-devel] [PATCH v2] util/id: fully allocate names table

[Eric Blake]

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On 11/25/2015 02:03 PM, John Snow wrote:
> Trivial: this array should be allocated to have ID_MAX entries always.
> Otherwise if someone were to forget to expand this table, the assertion
> in the id generator won't actually trigger; it will read junk data.
> 
> v2: Fix the range assertion, too. Compare against the known actual size
>     of the table instead of what it "should" be.

The v2 blurb would normally appear after the ---; it can be removed by
the maintainer.

> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  util/id.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

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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Re: [Qemu-devel] [PATCH v2] util/id: fully allocate names table

[Jeff Cody]

On Wed, Nov 25, 2015 at 04:03:37PM -0500, John Snow wrote:
> Trivial: this array should be allocated to have ID_MAX entries always.
> Otherwise if someone were to forget to expand this table, the assertion
> in the id generator won't actually trigger; it will read junk data.
> 
> v2: Fix the range assertion, too. Compare against the known actual size
>     of the table instead of what it "should" be.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  util/id.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/util/id.c b/util/id.c
> index bcc64d8..7883fbe 100644
> --- a/util/id.c
> +++ b/util/id.c
> @@ -29,7 +29,7 @@ bool id_wellformed(const char *id)
>  
>  #define ID_SPECIAL_CHAR '#'
>  
> -static const char *const id_subsys_str[] = {
> +static const char *const id_subsys_str[ID_MAX] = {
>      [ID_QDEV]  = "qdev",
>      [ID_BLOCK] = "block",
>  };
> @@ -53,7 +53,7 @@ char *id_generate(IdSubSystems id)
>      static uint64_t id_counters[ID_MAX];
>      uint32_t rnd;
>  
> -    assert(id < ID_MAX);
> +    assert(id < ARRAY_SIZE(id_subsys_str));
>      assert(id_subsys_str[id]);
>  
>      rnd = g_random_int_range(0, 100);
> -- 
> 2.4.3
> 

Reviewed-by: Jeff Cody <jcody@redhat.com>

Re: [Qemu-devel] [PATCH v2] util/id: fully allocate names table

[Michael Tokarev]

26.11.2015 00:03, John Snow wrote:
> Trivial: this array should be allocated to have ID_MAX entries always.
> Otherwise if someone were to forget to expand this table, the assertion
> in the id generator won't actually trigger; it will read junk data.

Applied to -trivial as a bugfix, with a trivial commit description
cleanup, removing this part:

> v2: Fix the range assertion, too. Compare against the known actual size
>     of the table instead of what it "should" be.

Thanks!

/mjt