Re: [PATCH 1/4] vmdk: fix maybe uninitialized warnings

[Laurent Vivier <laurent@vivier.eu>]

Le 05/10/2020 à 08:26, Christian Borntraeger a écrit :
> On 30.09.20 18:36, Fam Zheng wrote:
>> On Wed, 2020-09-30 at 17:58 +0200, Christian Borntraeger wrote:
>>> Fedora 32 gcc 10 seems to give false positives:
>>>
>>> Compiling C object libblock.fa.p/block_vmdk.c.o
>>> ../block/vmdk.c: In function ‘vmdk_parse_extents’:
>>> ../block/vmdk.c:587:5: error: ‘extent’ may be used uninitialized in
>>> this function [-Werror=maybe-uninitialized]
>>>   587 |     g_free(extent->l1_table);
>>>       |     ^~~~~~~~~~~~~~~~~~~~~~~~
>>> ../block/vmdk.c:754:17: note: ‘extent’ was declared here
>>>   754 |     VmdkExtent *extent;
>>>       |                 ^~~~~~
>>> ../block/vmdk.c:620:11: error: ‘extent’ may be used uninitialized in
>>> this function [-Werror=maybe-uninitialized]
>>>   620 |     ret = vmdk_init_tables(bs, extent, errp);
>>>       |           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> ../block/vmdk.c:598:17: note: ‘extent’ was declared here
>>>   598 |     VmdkExtent *extent;
>>>       |                 ^~~~~~
>>> ../block/vmdk.c:1178:39: error: ‘extent’ may be used uninitialized in
>>> this function [-Werror=maybe-uninitialized]
>>>  1178 |             extent->flat_start_offset = flat_offset << 9;
>>>       |             ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
>>> ../block/vmdk.c: In function ‘vmdk_open_vmdk4’:
>>> ../block/vmdk.c:581:22: error: ‘extent’ may be used uninitialized in
>>> this function [-Werror=maybe-uninitialized]
>>>   581 |     extent->l2_cache =
>>>       |     ~~~~~~~~~~~~~~~~~^
>>>   582 |         g_malloc(extent->entry_size * extent->l2_size *
>>> L2_CACHE_SIZE);
>>>       |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> ~~~~~~~~~
>>> ../block/vmdk.c:872:17: note: ‘extent’ was declared here
>>>   872 |     VmdkExtent *extent;
>>>       |                 ^~~~~~
>>> ../block/vmdk.c: In function ‘vmdk_open’:
>>> ../block/vmdk.c:620:11: error: ‘extent’ may be used uninitialized in
>>> this function [-Werror=maybe-uninitialized]
>>>   620 |     ret = vmdk_init_tables(bs, extent, errp);
>>>       |           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> ../block/vmdk.c:598:17: note: ‘extent’ was declared here
>>>   598 |     VmdkExtent *extent;
>>>       |                 ^~~~~~
>>> cc1: all warnings being treated as errors
>>> make: *** [Makefile.ninja:884: libblock.fa.p/block_vmdk.c.o] Error 1
>>>
>>> fix them by assigning a default value.
>>>
>>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>>> ---
>>>  block/vmdk.c | 8 ++++----
>>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/block/vmdk.c b/block/vmdk.c
>>> index 8ec62c7ab798..a00dc00eb47a 100644
>>> --- a/block/vmdk.c
>>> +++ b/block/vmdk.c
>>> @@ -595,7 +595,7 @@ static int vmdk_open_vmfs_sparse(BlockDriverState
>>> *bs,
>>>      int ret;
>>>      uint32_t magic;
>>>      VMDK3Header header;
>>> -    VmdkExtent *extent;
>>> +    VmdkExtent *extent = NULL;
>>>  
>>>      ret = bdrv_pread(file, sizeof(magic), &header, sizeof(header));
>>>      if (ret < 0) {
>>> @@ -751,7 +751,7 @@ static int vmdk_open_se_sparse(BlockDriverState
>>> *bs,
>>>      int ret;
>>>      VMDKSESparseConstHeader const_header;
>>>      VMDKSESparseVolatileHeader volatile_header;
>>> -    VmdkExtent *extent;
>>> +    VmdkExtent *extent = NULL;
>>>  
>>>      ret = bdrv_apply_auto_read_only(bs,
>>>              "No write support for seSparse images available", errp);
>>> @@ -869,7 +869,7 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
>>>      uint32_t magic;
>>>      uint32_t l1_size, l1_entry_sectors;
>>>      VMDK4Header header;
>>> -    VmdkExtent *extent;
>>> +    VmdkExtent *extent = NULL;
>>>      BDRVVmdkState *s = bs->opaque;
>>>      int64_t l1_backup_offset = 0;
>>>      bool compressed;
>>> @@ -1088,7 +1088,7 @@ static int vmdk_parse_extents(const char *desc,
>>> BlockDriverState *bs,
>>>      BdrvChild *extent_file;
>>>      BdrvChildRole extent_role;
>>>      BDRVVmdkState *s = bs->opaque;
>>> -    VmdkExtent *extent;
>>> +    VmdkExtent *extent = NULL;
>>>      char extent_opt_prefix[32];
>>>      Error *local_err = NULL;
>>>  
>>
>> Looks trivial, and correct.
>>
>> Reviewed-by: Fam Zheng <fam@euphon.net>
> 
> 
> Will this go via the block or trivial tree (cced). 
> 

Applied to my trivial-patches branch.

Thanks,
Laurent