Re: [PATCH 1/2] crypto: avoid overwriting Error object erasing keyslot

[Markus Armbruster <armbru@redhat.com>]

marcandre.lureau@redhat.com writes:

>> When erasing a keyslot we deliberately ignore some errors and
>> carry on trying to erase as much as possible. This results in
>> overwriting Error objects and triggering an assertion. Don't
>> pass in the &local_err, if errp is already set.
>> 
>> Fixes: https://gitlab.com/qemu-project/qemu/-/work_items/4697
>> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
>> Message-ID: <20261023141303.163893-2-berrange@redhat.com>
>> ---
>>  crypto/block-luks.c | 17 +++++++++++++----
>>  1 file changed, 13 insertions(+), 4 deletions(-)
>>
>> diff --git a/crypto/block-luks.c b/crypto/block-luks.c
>> index 0926ad28f0cd..8a1df846a146 100644
>> --- a/crypto/block-luks.c
>> +++ b/crypto/block-luks.c
>> @@ -1152,22 +1152,29 @@ qcrypto_block_luks_erase_key(QCryptoBlock *block,
>>  
>>      if (ret < 0) {
>>          error_propagate(errp, local_err);
>> +        local_err = NULL;
>>      }
>> +
>>      /*
>>       * Now try to erase the key material, even if the header
>>       * update failed
>>       */
>>      for (i = 0; i < QCRYPTO_BLOCK_LUKS_ERASE_ITERATIONS; i++) {
>>          if (qcrypto_random_bytes(garbagesplitkey,
>> -                                 splitkeylen, &local_err) < 0) {
>> +                                 splitkeylen,
>> +                                 errp && *errp ? NULL : &local_err) < 0) {
>
> I think the current code was simpler. error_propagate() will simpliy discard local_err if errp is already set. It is just missing "local_err = NULL;"

Moreover, *errp is wrong without ERRP_GUARD().

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