[v1] fix bugs reported by Clang Static Analyzer

[Qemu-devel] [PATCH for 2.10 06/35] qcow2: remove inconsistent check

Posted by Philippe Mathieu-Daudé 8 years, 3 months ago

This is equivalent to assert(russian roulette) so better remove it.

block/qcow2-bitmap.c:259:29: warning: The left operand of '==' is a garbage value
        assert(bitmap_table == NULL);
               ~~~~~~~~~~~~ ^

Reported-by: Clang Static Analyzer
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 block/qcow2-bitmap.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 3e8735a20d..fe72df5057 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -254,7 +254,6 @@ static int free_bitmap_clusters(BlockDriverState *bs, Qcow2BitmapTable *tb)
 
     ret = bitmap_table_load(bs, tb, &bitmap_table);
     if (ret < 0) {
-        assert(bitmap_table == NULL);
         return ret;
     }
 
-- 
2.13.3

Re: [Qemu-devel] [PATCH for 2.10 06/35] qcow2: remove inconsistent check

Posted by Eric Blake 8 years, 3 months ago

On 07/24/2017 01:27 PM, Philippe Mathieu-Daudé wrote:
> This is equivalent to assert(russian roulette) so better remove it.
> 
> block/qcow2-bitmap.c:259:29: warning: The left operand of '==' is a garbage value
>         assert(bitmap_table == NULL);
>                ~~~~~~~~~~~~ ^
> 
> Reported-by: Clang Static Analyzer
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>  block/qcow2-bitmap.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
> index 3e8735a20d..fe72df5057 100644
> --- a/block/qcow2-bitmap.c
> +++ b/block/qcow2-bitmap.c
> @@ -254,7 +254,6 @@ static int free_bitmap_clusters(BlockDriverState *bs, Qcow2BitmapTable *tb)
>  
>      ret = bitmap_table_load(bs, tb, &bitmap_table);
>      if (ret < 0) {
> -        assert(bitmap_table == NULL);

Rather, we should fix bitmap_table_load() to ensure that bitmap_table is
always assigned, even on error.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Re: [Qemu-devel] [PATCH for 2.10 06/35] qcow2: remove inconsistent check

Posted by Paolo Bonzini 8 years, 3 months ago

On 24/07/2017 20:42, Eric Blake wrote:
> On 07/24/2017 01:27 PM, Philippe Mathieu-Daudé wrote:
>> This is equivalent to assert(russian roulette) so better remove it.
>>
>> block/qcow2-bitmap.c:259:29: warning: The left operand of '==' is a garbage value
>>         assert(bitmap_table == NULL);
>>                ~~~~~~~~~~~~ ^
>>
>> Reported-by: Clang Static Analyzer
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>  block/qcow2-bitmap.c | 1 -
>>  1 file changed, 1 deletion(-)
>>
>> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
>> index 3e8735a20d..fe72df5057 100644
>> --- a/block/qcow2-bitmap.c
>> +++ b/block/qcow2-bitmap.c
>> @@ -254,7 +254,6 @@ static int free_bitmap_clusters(BlockDriverState *bs, Qcow2BitmapTable *tb)
>>  
>>      ret = bitmap_table_load(bs, tb, &bitmap_table);
>>      if (ret < 0) {
>> -        assert(bitmap_table == NULL);
> 
> Rather, we should fix bitmap_table_load() to ensure that bitmap_table is
> always assigned, even on error.

I think it's even better to initialize bitmap_table to NULL in
free_bitmap_clusters, as all other callers do.

Paolo