On 12/04/2021 17:48, James Bottomley wrote:
> On Mon, 2021-04-12 at 17:01 +0100, Colin King wrote:
>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>
>> The kzalloc call can return null with the GFP_KERNEL flag so
>> add a null check and exit via a new error exit label. Use the
>> same exit error label for another error path too.
>>
>> Addresses-Coverity: ("Dereference null return value")
>> Fixes: 830027e2cb55 ("KEYS: trusted: Add generic trusted keys
>> framework")
>> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>> ---
>> security/keys/trusted-keys/trusted_core.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/security/keys/trusted-keys/trusted_core.c
>> b/security/keys/trusted-keys/trusted_core.c
>> index ec3a066a4b42..90774793f0b1 100644
>> --- a/security/keys/trusted-keys/trusted_core.c
>> +++ b/security/keys/trusted-keys/trusted_core.c
>> @@ -116,11 +116,13 @@ static struct trusted_key_payload
>> *trusted_payload_alloc(struct key *key)
>>
>> ret = key_payload_reserve(key, sizeof(*p));
>> if (ret < 0)
>> - return p;
>> + goto err;
>> p = kzalloc(sizeof(*p), GFP_KERNEL);
>> + if (!p)
>> + goto err;
>>
>> p->migratable = migratable;
>> -
>> +err:
>> return p;
>
> This is clearly a code migration bug in
>
> commit 251c85bd106099e6f388a89e88e12d14de2c9cda
> Author: Sumit Garg <sumit.garg@xxxxxxxxxx>
> Date: Mon Mar 1 18:41:24 2021 +0530
>
> KEYS: trusted: Add generic trusted keys framework
>
> Which has for addition to trusted_core.c:
>
> +static struct trusted_key_payload *trusted_payload_alloc(struct key
> *key)
> +{
> + struct trusted_key_payload *p = NULL;
> + int ret;
> +
> + ret = key_payload_reserve(key, sizeof(*p));
> + if (ret < 0)
> + return p;
> + p = kzalloc(sizeof(*p), GFP_KERNEL);
> +
> + p->migratable = migratable;
> +
> + return p;
> +}
>
> And for trusted_tpm1.c:
>
> -static struct trusted_key_payload *trusted_payload_alloc(struct key
> *key)
> -{
> - struct trusted_key_payload *p = NULL;
> - int ret;
> -
> - ret = key_payload_reserve(key, sizeof *p);
> - if (ret < 0)
> - return p;
> - p = kzalloc(sizeof *p, GFP_KERNEL);
> - if (p)
> - p->migratable = 1; /* migratable by default */
> - return p;
> -}
>
> The trusted_tpm1.c code was correct and we got this bug introduced by
> what should have been a simple cut and paste ... how did that happen?
> And therefore, how safe is the rest of the extraction into
> trusted_core.c?
>
fortunately it gets caught by static analysis, but it does make me also
concerned about what else has changed and how this gets through review.
> James
>
>
